In need of help

Hello, I'm new to the sub so if this doesn't fit just let me know and I'll delete the post.

Could someone explain how this needs to be setup to be in the right position?I've tried to move it both ways and I didn't notice any change.

Turntable is a Philips 410 that I got from an aunt and didn't really tried to set up since it worked just fine but I recently got a slipmat and I wonder if I need to adjust anything because of its height. Thanks a lot.