How come my monitor only shows blue and yellow colors?

The problem is probably with your monitor, but i could be with your monitor cable and/or the video card in your computer.

First, check the cable connection between the computer and the monitor to make sure it isn’t loose.

If that doesn’t help, hook up the monitor to another computer, try using another monitor with your computer and try swapping out the video cable.

That said, if your monitor is almost out of warranty, you might want to contact Acer right away.