Setting up multiple Apple TV box in one home

We just moved into our new home. I have my first gen Apple TV 4K in our family room. I’m going to be setting up additional units in two other locations in the home, one of which I can see from my family room. Probably a stupid question but how do I pair each remote to only one unit? In other words I don’t want to push a button on one remote and change all three units. Thank you for your help