I have skydemon running on my galaxy s3 (android) and I am just about to start using Nexus 7. I am unable to change the rwy approach, if I tap the i button and then approach nothing comes up other than information designation grass/asphalt length ect,so currently the current approach is stuck on a rwy that I never use. I have checked the runway extension tab in set up but still cant choose/change to the runway in use on the day. Any thoughts chaps? what have I missed?

I have loaded on to nexus and everything work fine.

You don't need to select an approach; SkyDemon assumes you are making an approach to the runway you are "nearest" in the absence of an explicitly selected one. There isn't enough room for those tools on the phone version of SkyDemon.