You can really only change what is displayed in the lower (blue) line - you have to click through this line to change what is there.
I would like to have NDL instead of dive time displayed on the watch faces as i REALLY don't care if i'm 4 or 40 minutes into my dive, but i'd sure love to know when i have 2 minutes left of my NDL...
Remember (depending on which dive view you're on) you also have the graphic around the edge of the screen, so if you're in the gas screen, the out graphic will show NDL, in NDL then the graphic will show gas contents.
The Suunto Manual doesn't give much info. You can set 4 views NDL, Gas, Compass and Timer - in the bottom window, you can then choose what additional info you'd like. The small right hand data window might also change - I don't' know I don't' have a D5.
I know on my Eon I have 2 configurable data windows which I can scroll though different data - and this changes depending on what view I'm in. It did take a few dives to get it to my liking , as what felt right on the surface behind a computer didn't alway seem the best underwater when using it. We're all different, my wife "demands" her's is set up differently to mine because she has different preferences
When you've had a play, let me know as I'd be interested to hear if you can set it up the way you want