Samsung Galaxy Multi-Window, I want my money back.

Both of my sons are now bypassing any timelimits on their samsung galaxy phones, they have figured out that if you just use the build in multi-window feature they can split the screen with the norton and any other app to continue to use their phones, and i've spent way too much time already trying to figure out if there is a way to disable this feature on Samsung and there is not a toggle to completely disable the feature.  I literally bought my norton subscription just for norton family and am pulling my hair out and wanting a refund.