So, I finally got WiFi at my home... however, it seems that when anyone else in my family is connected to it as well, instead of connecting to the main router at the house, my phone autonatically connects to their 4G or 5G network.

If you don't mind helping, what I want to know is how to prevent my phone from connecting to theirs and to stay on the actual router.

I have a HTC One M7, not sure if that makes a difference.