I can control the temp for water going to the tub but when I use the shower I just get scalding water and can't control/change the temp. Same controls I'm just diverting the water why would I only get scaling water from the shower.

If the water is the correct temperature for the tub diverting it to the shower should not change the temperature. Can you give me the brand name of your tub/shower valve?
If you can't give me a model number tell me how old it is. Any more details would be very helpful. Back to you, Tom