Trace problem in Mathcad 13.1

I apologize for using such an old version, but that's what I have. I saw a post from 2009 about not being able to assign properties to traces. I have this problem now, although don't recall having it in past years. I upgraded from 13.0 to 13.1 yesterday -- didn't solve the problem.

When I click on the pulldown menu for

symbol

symbol weight

line weight

the menu appears but when I mouse to select the menu disappears and I can't assign any of those properties to a trace.

I tried opening a new sheet and making a very simple plot with just two traces; same behavior.

Any ideas?

Thanks