When i'm home and my iPhone rings, it rings on all the iPhones in my house along with my iMac , how do i stop this?

That is a feature of Continuity

To turn it off go to Settings > FaceTime and change "iPhone Cellular Calls"to off.

If the phones are used by different individuals you may also want to consider using different Apple IDs for each person and investigate the new family sharing features https://www.apple.com/icloud/family-sharing/

Sounds as if all the phones in the house are sharing the same iCloud ID. This is part of the Handoff/Continuity feature. The best solution is to have a separate iCloud ID on all devices, however, you can go into Settings>FaceTime>iPhone Cellular Calls>OFF on all of the devices. That will prevent them all from ringing. You will have to look somewhere else for info on changing the iMac, since I'm not a Mac user.