If your shower sprays freezing cold water when the dishwasher or washing machine kicks on, or scalds you when someone flushes a toilet, you have two basic choices:

1) Organize shower schedules with appliance schedules or...

2) Have a pressure-balancing valve installed on the hot and cold water lines that supply the shower faucet. Unless you're quite familiar with doing your own plumbing work, this is a job for a plumber.