Changing Grey Background

Hello, I have two quick questions

a.) How do you change the default grey background? I would prefer a lighter color instead of grey.

b.)What color do you use for your onion skin? Im a little frustrated, I cant seem to get the onion skin to work the way I want. All I want is to see the previous drawings but still see what Im currently drawing. I change the onion skin color to something lighter but its still not showing up as light as I would like it to so I can draw. Any ideas?

Go to preferences>General>edit colours on the LHS and you can change the colours for a whole load of stuff. You have to close then reopen to get the change.

There is no edit colours tab