invalid username or password

hi all! I've changed my username, logged on through the browser but every time I try and start a new game it comes up with "invalid username or password". any ideas why?

Maybe a saved password in the browser? 

Probably. Try deleting your browser's cache.

The place the cache is cleared may have a way to clear passwords but it may be in a different area.

Any time that I've cleared my cache, I've had to relogin any sites that I had my password saved on.

Yeah, it depends on how the passwords are saved. On my mobile browser, I can check or uncheck if passwords are cleared the same time I'm doing cache. Firefox on my desktop has those in separate functions all together.