How do I limit the number of outline levels displayed?

I’d like to be able, in a large outline with six levels, to display only the first level, only the first two levels, etc. The offline help says (if I understand it correctly) that I can do it with the Navigator – just call up the Navigator, click on “Heading Levels Shown,?” and select a number. That is not working for me.
Any thoughts on how to do this?

2 Possibilities

Reduction of number of displayed outline levels in the Table-of-Contents:
Right click into the table > select Edit Index/Table > tab Index/Table > set Evaluate up to level to 2.

Reduction of numbers shown in the headings:
Tools > Outline Numbering > tab Numbering > Show sublevel set to 2