PFD: assuming this is the standard display page, pushing the rectangular button on the left displays the labels for all the rectangular buttons (second picture) for about 3 seconds.  Pushing the left-most rectangular button again toggles you through the next 3 screens, in turn.  One more push and you're back to the full PFD screen

PFD	PFD with screen labels (disappear after ~3 seconds)	PFD and partial DG	PFD and HSI
PFD and partial engine data

MAP: while the labels are displayed (in any screen), pushing the second left-most rectangular button -- labeled "MAP" in this context -- toggles you through the following 3 screens.  One more push and you're back to the "partial DG" screen

Partial DG (also shows TIS and WX, I believe)

DG (not sure about what else can be overlaid)

HSI (not sure about what else can be overlaid)

Moving map  (also shows TIS and WX, I believe)

ENG: while the labels are displayed (in any screen), pushing the third left-most rectangular button -- labeled "ENG" in this context -- toggles you through the following screens.

Full engine monitoring screen

Partial engine data and partial DG