java - Unsupported major.minor version 52.0 - while using a lower version to compile. How is it still going bad?

I get this error message when I try to run my program:

Exception in thread “main” java.lang.UnsupportedClassVersionError, Unsupported major.minor version 52.0

I am using Eclipse. I tried going to Windows -> Preferences -> Compiler and changing my Compiler compliance level to a lower version, all the way down to 1.3, the lowest. I also tried configuring the project specific settings and doing the same thing.

I checked my Java version and I am running 1.7.

52 should be JDK 8 I believe, but if I compiled it in 1.3, why is it saying I'm using JDK 8?

Sorry there are other questions like this, but none of their solutions have worked for me.