A form will always add a new row every single time. It’s designed that way. Because of that, a form may not be the best choice here.
- What I would do is maybe try a Link to Screen button with the ‘This Item’ option. This will give you a new screen connected to the same row (assuming the user is already viewing their detail). Then they can edit their details through entry components on that screen.
- Another option is to just turn on editing for the user profile and only display the edit button if the signed in user matches the profile email. This is the original and simplest way to allow a user to edit a row.
I like the Link to Screen option because it gives you more options but requires a some extra columns to make it work nicely, but the Edit option is a lot easier to use. I would take a look at this example for some ideas.