[imhoguy]

Please don't! The worst thing is to swap meaning of a button at exactly same placement. If you are forced to do it then at least change background color and add some icon etc.

But nothing can beat MS Teams "Close" document preview button, which once clicked, uncovers chat "Call" button. Add some laggy nature of Teams and you call the entire channel/chat just by trying to close an opened document with too many clicks.

[darkwater]

But that would not change "immediately". Basically if you never logged in (in that browser) you see the "Sign up" more prominently and once you registered, you are already logged in (so you don't see anything at all) but if you do log out, then you would see the "Log In" clearly (and the "Sign up" will be somewhere also but not in the best spot).