Confused operator

Hi folks,
I'm using a HOG 3 for the first time on a 3-day show. I used to run a Hog 2 and currently run Grand MA's and Compulite Vectors.
I'm stuck!

I cannot consistently clear my programmer after editing a cue in a cuelist. I change my cue, update and then press CLEAR. It doesn't always clear the programmer. Sometimes it seems to do something like an UNDO.
Even if I do manage to clear it, I can sometimes press CLEAR and it does the UNDO later on.

Is the CLEAR key supposed to function as UNDO? Do I have something set wrong in preferences??

Other question, how can I stop an effect in a cuelist. Cue #1 is a pan effect, cue #2 is a blackout with a fixed pan position. The effect continues when I go to cue #2.

Any help would be appreciated. I'm stumped.

Dave
Related