When I changed the version from 1.8.1 to 1.7.10 or any other version, my minecraft would always crash

Put the summary of the bug you're having here

What I expected to happen was...:
My minecraft would open and I could go onto servers, or open my own worlds.

What actually happened was...:
What happened is once I chose a server or world my minecraft would close and open a crash report.

Steps to Reproduce:
1. Click "Edit Profile"
2.Click "Use Version-1.7.10"
3. Open Minecraft
4.Click on a server or world