
At 17 weeks he is still very young :) Take him back to the absolute basics.....take him outside every 15 minutes or so and give him the command that you will use (I say 'Hurry Up!' ) ...when he performs , fuss him up and make sure he knows he has done the right thing.
If he pees in the house (which he probably won't IF you take him out often enough) , don't make a fuss , just take him outisde and give the command.
Clean any pee up with warm water and biological soap pawder to get rid of the smell. Don't tell him off if he does pee in the house ...but keep on making a huge fuss of him when he performs outside , he will soon get the idea.
Make sure you TAKE him out though , don't expect him to take himself out
HTH
Melody :)