You can edit your own posts to update the caption or tags.
Steps:
Find the post you want to edit.
Tap on the three dots (⋮) icon on your post.
Select Edit.
Make your changes, then tap the checkmark in the top right to save.
Good to know:
You cannot replace images or videos after posting — only the caption and tags can be edited.
If you need to change the media, delete the post and create a new one.
All edits must comply with our Community Guidelines.