Verified answer

You can do it if you have a desktop link, switch to desktop and then edit add details under the question and then switch back to mobile.

If you do not have the desktop link you can't do it you will need to use a computer.

Try doing it the same way as you do on a computer:

Find the question you asked

click on the pencil icon

choose "add additional details"

I've never tried it before, but it just might work :)