Lowering a boosters signal.

[CharlesXavier]

So family friends moved into our house, them being far away from the router made their signal terrible, so they bought a booster, this seemed to give them 4 bars but the original connection 2 bars, I am able to connect to the booster but i like to feel that they don't have control over the connection i am using and i would like to stick to the original. Im asking, is their anyway to lower their signal strength to allow the original to increase?

Can i do this remotely as i don't have physical access


- Thanks.