Can you put in 15 amp outlets with 12 gauge wire on a 20 amp circuit these are just regular household outlets not used for dryers or refrigerator. Or should I replace with 20 amp outlets

Sure, that is more common, than 20 Amp recepticles on a 20 Amp Circuit. Go Figure.
You can't put 20 Amp Recepticles on a 15 Amp breaker.