cpp file cannot find header file declared variables

I am new to Unreal and C++ coding, and I am currently working on simple graphics settings, currently following this tutorial:

However, even though i did the EXACT SAME THING as the video says, my cpp files are unable to find the header variables. I’ve been stuck on this for a few hours by now, and I’m stumped. Here are some screenshots:
CPP:


Header:

Thanks!

You need to add the class name before the function name like void myclassname::myfunction() in your .cpp

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