Hi Lucy
The way uderstand it you will need to create 8 buttons not 4.
4 blue buttons 'blue_1, blue_2,blue_3,blue_4 'that are visable on entering the slide and 4 red ones in the exact same position but set to not be visible on output.
You then need to create an advanced action for each blue button. The action will jump to a slide + Hide blue_1 +Show Red_1.
I presume the slide you jump to has some form of back button. Once you return the blue will be turned off and the red will be turned on (as the action has made this happen)
Hope this makes sense
Thanks