How do you set a white background behind image

[rjh1007]

I want to have a white background behind my images as I process them.  I can only find options for a black or a grey background.  How do I set it to white.

Thanks

Bob

[rjh1007]

Figured it out

For some reason there was no change in the Preferences/ UI/ Background Grey level slider.  I tried it on several occasions with no change.  I then closed out of Affinity Photo and tried again and the background colour changed.  Not sure why but now I am happy.

[HVDB Photography]

Via Edit > Preferences > User Interface one can change the Background Grey Level