# Edit slides, captions and alt text

URL: https://blackbox.plus/guides/edit-slides-captions-alt-text
Level 2: Make your first post (https://blackbox.plus/guides/make-a-post)
Updated: 2026-11-04
Time: about 5 minutes
You'll end with: Slides, caption and alt text the way you want them, with nothing left on Check
Do it in Blackbox: https://blackbox.plus/app/plan

> Change the words on any slide, add or reorder slides, write the caption and add alt text, so people who use a screen reader know what each image shows.

## Short answer

To edit a post in Blackbox (blackbox.plus), open it from Plan and click Edit slide on the preview. Click the words on a slide and type; a slide fits a 70-character headline and 35 words in all, and it saves when you click away. To have them rewritten, click a chip such as Shorter or Stronger hook, or say what to aim for and click Rewrite; nothing changes until you click Keep. In the strip of slides you can reorder, add, duplicate or delete, keeping a carousel between 2 and 10 slides, and Undo, Redo or History brings back any change. Under Alt text, describe what each slide shows, up to 1,000 characters. Then open step 1, Caption, write it, and use Refine to change it the same way. Suggest hashtags offers some to tick, and the first press is free. Posting to Instagram and TikTok together splits the caption into two tabs. A scheduled post is locked, so unschedule it first.

## You'll need

- **A post or carousel in Studio.** Made from an idea or uploaded, in Studio. (Guide: https://blackbox.plus/guides/make-instagram-carousel-with-ai)
- **Not scheduled yet.** A scheduled post is locked. Click Unschedule on its Post step first if you need to change it.

## How to edit slides, captions and alt text in Blackbox

1. **Open the slide editor.** Open the post from **Plan** and click **Edit slide** on the preview.
   You'll see: The editor, open on that slide.
   Starts at: https://blackbox.plus/app/plan
   ![The slide editor: the slide large in the middle, Regenerate this slide, Undo, Redo and History along the top, the settings on the right, the strip of slides below, and Slide 1 of 5 ringed](https://blackbox.plus/guides/edit-slides-captions-alt-text/01-editor.png)
2. **Change the words.** Click the words on the slide and type.
   You'll see: A counter for the 70-character headline and 35 words in all.
   ![A slide in the editor with the counter under it ringed: characters used of 70 for the headline and words used of 35](https://blackbox.plus/guides/edit-slides-captions-alt-text/02-words.png)
3. **Or have them rewritten.** Under **Words**, click a chip such as **Shorter** or **Stronger hook**, or type a note under **Anything to aim for?** and click **Rewrite**.
   You'll see: **Rewrite** beside your note, under the five chips.
   ![Words: the five chips Shorter, Stronger hook, Add a call to action, In the brand’s voice and Fix grammar, a note under Anything to aim for? — mention free delivery before 8am — and the Rewrite button ringed](https://blackbox.plus/guides/edit-slides-captions-alt-text/03-rewrite.png)
4. **Keep or discard the new words.** Click **Keep** to put the new words on the slide, or **Discard** to leave it as it is.
   You'll see: The new words beside **Now**, the slide’s words today, with **Keep** and **Discard** under them.
   ![The slide’s words today under Now beside the new words about free delivery before 8am, with Keep and Discard ringed](https://blackbox.plus/guides/edit-slides-captions-alt-text/04-keep.png)
5. **Arrange the slides.** Drag slides in the strip to reorder them, or use the **‹ Move ›** arrows, **+ Add**, **Duplicate** and **Delete**.
   You'll see: The slides in their new order, saved on their own.
   ![The strip of five slides at the bottom of the editor, with Move, + Add, Duplicate and Delete ringed](https://blackbox.plus/guides/edit-slides-captions-alt-text/05-arrange.png)
6. **Add alt text.** Under **Alt text**, describe what the slide shows, as you would to someone who can’t see it. Click **Done** when you’re finished.
   You'll see: The post again, with your slides updated.
   ![The Alt text box in the editor, ringed, describing the cover slide in one sentence](https://blackbox.plus/guides/edit-slides-captions-alt-text/06-alt-text.png)
7. **Write the caption.** Open step 1, **Caption**, and write the caption.
   You'll see: Counters under the caption for 2,200 characters and 5 hashtags.
   ![Step 1, Caption: the Instagram caption with the character and hashtag counters ringed, and Refine and Suggest hashtags under it](https://blackbox.plus/guides/edit-slides-captions-alt-text/07-caption.png)
8. **Refine the caption.** Click **Refine** and pick a change, such as **Shorter**. Click **Keep** to use the new caption, or **Discard**.
   You'll see: The new caption under yours, with **Keep** and **Discard**.
   ![The caption refined with Shorter: the shorter version shown under the caption, with Keep and Discard ringed](https://blackbox.plus/guides/edit-slides-captions-alt-text/08-refine.png)
9. **Add hashtags.** Click **Suggest hashtags** under the caption, then tick the ones you want.
   You'll see: Hashtags to tick, each one you tick added to the caption.
   ![After Suggest hashtags: Suggested hashtags to tick under the caption, ringed, with Suggest again beside the heading](https://blackbox.plus/guides/edit-slides-captions-alt-text/09-hashtags.png)
10. **Write the TikTok version.** Posting to Instagram and TikTok together? Open the **TikTok** tab under **Caption** and click **Write the TikTok version**.
   You'll see: TikTok’s own **Title** and shorter **Caption**, which you can edit.
   ![The Caption card on its TikTok tab after Write the TikTok version, ringed: a title and a shorter caption written for TikTok](https://blackbox.plus/guides/edit-slides-captions-alt-text/10-tiktok-caption.png)
11. **Check what is left.** Open step 2, **Check**.
   You'll see: What is left: the caption, slides still drawing, or a slide without alt text.
   ![Step 2, Check, under Before it goes out: caption written, all slides rendered, alt text on every slide](https://blackbox.plus/guides/edit-slides-captions-alt-text/11-check.png)

## Good to know

- The five chips are Shorter, Stronger hook, Add a call to action, In the brand’s voice and Fix grammar. The caption’s Refine menu has the same five, and each uses one of today’s rewrites.
- The first Suggest hashtags is free. Suggest again asks for a new set and uses one of today’s rewrites, as Write the TikTok version does.
- Regenerate this slide, at the top of the editor, writes new words for that one slide in the same layout and style, and a new picture when that slide has one; it uses one of today’s rewrites, or a picture, and isn’t charged if it fails. Redo all slides, on the post, rewrites every slide and the caption; slides marked Keep as is stay.
- One caption by default. The Instagram and TikTok tabs appear once both kinds of account are picked on the Post step. Leave TikTok’s empty to use the Instagram caption.
- Track visits from this post adds tracking to your ask’s link, so visits from the post show up in your site’s analytics.
- There is no Save button: each change saves on its own, and History keeps the version before every edit, with the name of whoever made it.
- Under Layout, you can move the words to the Top, Middle or Bottom, or make the headline Smaller or Larger.
- Alt text is up to 1,000 characters, and Blackbox sends it to Instagram with each picture. Missing alt text is a reminder on Check, not a blocker.
- With your own uploaded pictures, the button says Edit slide (Arrange slides on a video as uploaded), and the editor reorders and deletes them.
- A carousel holds 2 to 10 slides.

## Official docs

- [Instagram: alt text and carousel specs](https://developers.facebook.com/documentation/instagram-platform/instagram-graph-api/reference/ig-user/media)
- [TikTok: photo post title and description](https://developers.tiktok.com/docs/en/content-posting-api-reference-photo-post)

## Questions people ask

**My caption gets cut off on Instagram**

Instagram shows only the start of a caption until someone taps more. Put the point in the first line, say one thing, and end on what to do next.

**Check says a slide has no alt text**

It is a reminder, not a blocker. Alt text is read aloud to people who can’t see the image — open Edit slide and describe it under Alt text. It takes a minute.

**I want a different caption on TikTok**

Pick both your Instagram and TikTok accounts on the Post step, then open the TikTok tab under Caption and click Write the TikTok version, or type your own. TikTok gets its own title, up to 90 characters, and its own caption.

**There are no hashtags under the caption**

Hashtags are suggested only when you ask. Click Suggest hashtags under the caption; the first set is free. Write the caption first if the button is greyed out.

**It says Not saved**

The words did not fit the slide: a headline is required, it fits 70 characters, and a slide fits 35 words. The message says how much to cut.

**I changed something by mistake**

Click Undo (or press ⌘Z), and Redo (⌘⇧Z) if you went back too far. For anything older, open History, which shows who made each change, and click Restore next to the version you want.