Just to clarify, could you post the number of your OS version (e.g. 1.6 or 1.7). There has been confusion, see:
You can find out your OS’s version in the Fairphone Update app (mine says e.g. Fairphone Cherry 1.6.
I do not have Google Apps installed, and I also don’t have the issue of preferences being lost. On the one hand this could easily be intended behaviour, so to lower energy consumption of smart phones.
On the other hand I do not want to blame everything on Google: Do you have other apps installed, which could somehow interfere with the energy/display settings?
Greets, Stefan
Edit: If it doesn’t bother you too much, you could just use the quick access button in the notification bar. To do so, slide the notification bar down and click on the upper right button (reassembling squares). The button which toggles the sleep function is the one which says something like “Duration”. One blue indicator means 15 seconds, two mean 30 seconds and three mean 1 minute until sleep mode.