Help with my puppy and older dog fighting

I have a 4 1/2 month schnoodle puppy and a 9 year old schnoodle. Have had the puppy Cody for 2 months. Riley my older dog does not like him at all. Of course Cody wants to play and jump on Riley’s back. They get in mouth fights constantly. The last few days I have just been stopping it when it gets too rough. Nobody has ever gotten hurt but I think I might have let it go on too long- now have to fix it. Any suggestions. They will both lay with me in the chair when they are sleepy so I don’t think they hate each other. Both seem to be toy aggressive too. I know Riley is from previous experience. They both want the same toy. Please help!!