Here's a video guide on the bucket fill tool to help out.

I THOUGHT IT WAS JUST ME

Bruh

It leaves white pixels because the tolerance is low, just turn up the tolerance! Hope this helped! :D

I agree it does that to me as well.

Set it to "smart"

for some reason its filling to whole entire thing when I only want it to fill this one tiny space.

Play around with the settings.

smart 47 works the best for me

I had this problem before, but then i found out about smart mode.