Graph editor question

The audio is very low and a little hard to understand. But I get the idea. I'm glad you figured it though. So what was going on? How did you mirror it and with which of the mirror options?

That is the MOST confusing menu in Blender.
I'm glad you figured it out - but the easiest thing to do is to put the playhead on that same keyframe and then choose the top one.  "By Times over current frame."

But here is a short explanation of this.

"Times" is horizontal - or the X Axis (in the GE)

"Values" is vertical - or the Y Axis (in the GE)

The rest should be easy to figure out from that.