>> I usually have the RGB setting in color settings/working spaces/RGB set to: 'monitor RGB
That is never recommended here — try setting a device independent Working Space like "sRGB 2.1..." as your Working RGB (until you better know what you are doing).
>> white now appears yellow on my screen, even though when I look in color picker and select white, the numbers are correct - 255,255,255
That is a sure sign of a bad monitor profile in Photoshop, you need to reprofile your monitor and get it engaged in System Preferences> Displays> Color> Display Profile (or Windows equivelent) — Photoshop/Adoe apps will pick it up from there for color-management purposes.
>> I have tried changing to other settings but white still looks yellow
I don't know what that means, 'whites appear yellow' is a FAQ...
Try these settings:
Picture 1.png 61.1 K
Thanks, but I have tried those settings. White is the only color that is off - it appears yellow and only within photoshop - white is white when photoshop is not running.
I am experiencing the same problem, and Dude, I also got a Dell. Do you think this a software or hardware malfunction?
Sounds like you need to calibrate your monitor. I have a Dell 2007WFP and all of the setting options in the onscreen menu are rubbish. When I recalibrated the Dell I got a great result. For more on colour set up in Adobe Suite