You can see and change each track's path to the left of the track. In your screenshot, it's
.:frame for the top track, and
.. for the bottom track.
For a normal track (like the top track), this path consists of a node path before the
: and a property specifier after.
Naturally, for a call track (such as the bottom track), there is no property specifier. The node at the assigned path will have the function called on it.
The node paths are relative to the Root Node set in the AnimationPlayer node.
So, if the Root Node is set to
.. and you want to call
setWalking on the
Player node, you should set the path to