when filling in forms I'd like to be able to choose my name from a dropdown

[bigdan]

I assume this is a simple question.

When I'm filling in forms online if I get to email I get a kind of pop-up where I get to choose which of the emails I've used in the past I'd like to use. For name I don't have that option since I've always used the same name, but I'd like to change that now to not include my last name. How would I do this?