Our sister to yours - 3051S has Velcro sewn on the backs and seat cushions along with the other half of the Velcro to stick them in place. There are two on each cushion.
Our 2017 did not have velcro from the factory. I used a strip of sticky back velcro along the length of the seat cushions near the back edge to resolve that issue.
Keep in mind the hinged wood panel should be up in the dinette configuration.
I tried various options with the existing dinette seat cushions. Velcro helped, but the seats were uncomfortable for anyone riding many miles in the dinette, which is the case when we have 3 or more folks on the trip. My wife and decided to replace our dinette with theater seats that recline:
Linear Mode
