Tempo change won't "stick"

Sure thing David.

Here's one:

1. I open the Lines palette, and drag a guitar position object (the object that has VII by default) to the score.
2. I double click on the line of the object, putting it in edit mode (incorrectly thinking that's how I change the properties of the line).
3. I right click for a menu.
4. The line disappears.

The line will reappear if I do some operation (like add another guitar position object to the score). But refreshing the screen won't make it visible.

Moving on...

1. I right click the line to get rid of the hook.
2. I uncheck the hook box, click OK.
3. The hook disappears.
4. I move another guitar position object onto the score. It's missing the hook, but I want one on this line.
5. I right click on its line to check the properties, and notice the hook box is check, and the height is 1.50.
6. So I check my original line's properties, and it shows the hook box checked as well, although there's no hook.
7. Exit the program and restart it.
8. Now if I check the line properties on both lines, they show hook checked but with height of 0.
9. I right click my second line to set the hook height; I set it to 1.50, click OK.
10. The hook does not appear. I recheck the properties, and it shows the height at 1.5, but there's no hook.
11. I close the program and re-open.
12. Both lines have no hook; both have hook checked; one has height of 0.00, the other 1.50.