I have a old shower with 4 handles, two to turn on the tub water and two to turn on the shower water. The water for the shower will not shut off. Is there aqn easy way to fix this with replacing all the fixyures ?

Any chance you can post a picture or tell us brand/model? Is there a diverter that you pull/ push/twist to switch over to shower? I am thinking that you could possible have two totally separate valves with their own supply lines. I would close the main, open all valves and remove the stem or cartridge. Sounds like you have a bad washer or cartridge seal.