If you are still configurating it maybe this can help you. Taken from Znote's Post:
Problem shooting:
I got some problems here, i could not login with my new username.
How I fixed this:
Click "stop UniServer"
and then click
"start UniServer".
If that does not work, try to do a computer restart to clear out the cache. Or click ctrl + F5 to reload phpMyAdmin without cache.
If reloading site without cache does not work, reboot your computer,(to control check that the programs are properly turned off) And then login again. Make sure you login with your correct new username and password and not root!
After a computer reboot it worked for me, and I got in