Dog staring

I'm being driven crazy over this because I know he wants something and the only words his old owners left him knowing were "Potty" and several variations of "Food time" (They only took him out for him to go potty by their own unprompted admission so he doesn't know "Walk")

He doesn't play much unless he initiates it. I have tried on several occasions to initiate it after staring to no effect

I always check his water dish multiple times a day and either add new or clean the dish and replace the water.

I give him attention including brushing him frequently including when he stares

The only other thing I can think of is that he wants up on my bed and that only works half the time.