Youbee,
You have to pop the glass mirrors out to access the retaining clips for the mirror covers.
Use the mirror positioning switch to point the mirrors slightly downwards & you'll be able to get a small flat head screwdriver behind the glass which will allow you to prise the glass off its mount.
Then you can see the clips retaining the mirror casings, use the screwdriver to prise the clips out (do it gently to avoid snapping the clips)
Refitting is reverse of removal & then push the glass back on its mounting....The glass is clipped in.
Don't attempt it without taking the glass out as you'll just snap the housing retaining clips off
Cheers