I’ll try and explain.
Have 2 different tracks with a midi clip on both.
Double click on the first to bring up the piano roll editor. Press selected and you can click either clip on the arranger to switch between them.
Press draw and when you select the other clip it does not switch to it.
Close the piano roll and open it again.
Draw is selected on the tool bar and you can now click on either clip to switch to it.