Quick Keys are what you need to understand. They are similar to bank switches in concept - keep in mind that FS as a default has all of them turned on when you allocate a new system. The trick here is that YOU must allocate at least one quick key to turn things on/off.
Let's start with conventional first - you have a system under which you have your groups. How you allocate your group quick keys is up to you - but you should have at least 1 group quick key allocated for every group you define. It is possible to have the same GQK assigned to multiple groups. You can then go to the system form and look down/center - make sure that for every GQK you have allocated, there's a check mark. Pretty simple here
Now you must assign a system quick key, which is done on the system form. Once you have allocated a system quick key, go up to Tools/System Quick Key Editor and hit Auto Select. Float your mouse next to or on top of the box where your quick key is assigned, and look to the right at the blank area. This will show you your quick key allocations as you have them so far. We'll come back to that in a moment.
Now about trunking - the XT scanners do this at the Site level. When you allocate a system for a trunk, it's really more of a logical placeholder. Remember that in the XT world, you can have multiple sites per system. Each site needs its own Site Quick Key, and each group its own Group Quick Key. Notice on the Trunk System form, there's an area for enabling the Group Quick Keys near the top center. As in the conventional world, each group which contains talkgroups would need at least one Group Quick Key. The kicker here is that for every site you define, each one shares all of the groups.
Now remember that System Quick Key Editor? Once you have defined all your sites and groups, go back and use it again (always Auto Select it to refresh it before using it to document). You will be able to see how your site and group quick keys are now laid out.
There's a LOT more to it than this - I deliberately did this KISS style. I didn't even try to tackle number and startup keys....
I think I'll stop there...got that so far? Mike