The title of the best seller gig can be edited?
You can edit the title but the URL won’t change. Which is a decent reminder by Fiverr that you shouldn’t edit in a way that you, for example, made a gig to sell logos, got reviews on that gig, and then change the gig to sell app development, because that’s not what the reviews were for, and it might be seen as deceiving the customer who’d think you got the reviews for app development, while you got them for logo design.
Editing a title to sell the same thing as before but to integrate better/other keywords, or because there are spelling errors, or you thought of a way to make it sound better in some way, of course, is fine.
A note to your thread title - I usually pass such titles by and don’t click them, as do many other people. It’s better to put something more concrete in the title of a forum post than “Can you tell me?”
With a title like that, you expect people to waste their time by clicking the thread to see what you want to be told, only to find out that they can’t tell you.