@appi I am going to remove goto and see how's it going on now.
If you are able to make use of functions, it will be easier to see how to get rid of the goto's. As I mentioned earlier, a function encapsulates one idea with 1 Line Of Code (LOC) to call it. When trying to simplify code, you can sort out several ideas with several LOC, rather than lots of detailed code.
I think the choice of variable name could be causing some confusion - is SignUpUsers a good name for the user's new login name? Is this the same thing as UNameLogin ?
A good way of designing code in the first place, is to write pseudo code. This is a list of comments written out like a recipe if you like. Start out with some general statements of what you want to do. Then go back back and refine it by adding more detail, until you are happy to convert it into code. Leave the comments in, they could serve as documentation. Doing things this way helps identify what should be in a function, where to put loops, and gives some clues as to what your variable & function names should be, also the types of the variables.
UNameLogin is already created by me. Yes, SignUpUsers is the user's new login name. SignUpUsers should be recognized in real login after the user creates the new username. The problem is that real login doesn't recognize SignUpUsers but it only recognizes UNameLogin.
I only removed goto Username2; It seems to be better.