It took a second or two, but I figured out what you were trying to say anyway. 🙂
If you want to edit a toot, click the 3-dot ellipsis thingy below the toot and to the right, then click "Delete and re-draft". (You need to open the toot in the web to see that thingy.)
Yes, if you delete/re-edit then it's like a new toot and any favs, boosts, and replies get lost (the replies just get dumped back into the public timeline).
If I've only had someone favorite the toot and no other interaction, then I don't worry so much about re-doing it to fix something, but if people have replied then I will just let it go or put a correction in the thread when the typo causes ambiguity or confusion, or if something else has to be addressed with the toot.