Why am I having problems with my wireless internet all of a sudden?

About two months ago one of my brother in laws changed it do a different channel or something. Ever since then my internet is really bad in my room but fine in the room next to my router. Is it something to do with this channel change? or is it something else. It still works in my room, but its a lot more slow. it loses connection sometimes. Buffering videos takes a lot longer and its very frustrating please help!!!