I leave my beer fridge set at 40 degrees and serve at around 10 PSI.
The beer will be carbed after a week at your settings.
Don't know how you are serving the beer (cobra tap or faucet on side of fridge, etc.) or the length of your beer line from keg to faucet, but if you bought the standard cobra tap set-up with a 5 foot line, the beer pour might be a little foamy at 11-12 PSI.
If it is, just turn the gas off and use the pressure relief valve in the keg to bleed off some of the gas pressure, might have to do it a few times over a few hours. Then turn the gas back on and set the serving pressure a couple of pounds lower.