When making a motion tween, the graph below the timeline wont let me access any other options than X

I have a simple animation that I'm working on, and I need to addjust the path of an object, but the part I want to change is in the Y axis. The program simply wont let me click on the option (Photo included). I clicked on all the options, but it wont go out of X. I also tried clicking on the other lines, still did nothing.