Ability setting

I just started a couple days ago and I'm a bit confused about something...
I got stealth while leveling mining, according to the game I should have learned the ability on my other DoHs but I cant add them to my toolbar/macro bar.
Can I learn it only on one of the three? Should I be holding a key as I click to add it to the bar? Is there something else that I'm missing?

You can only set traits on DoL/H not abilities.

So how do I use stealth on my other DoH? I was supposed to learn it at lv 8 ^^;

Only Disciplines of Land get Stealth, not Hand. Assuming you meant Land, in each case you need to get that discipline up high enough to get it. If you unlocked it on Miner, you can't use it on botanist unless you unlock it there.

I sorry I hit DoH when I ment DoL, I'm lv 15 miner and herb. Yet I can't use stealth because its not on any of my 3 hot key bars. When I click on abilities/traits tab it is lit up as though I can use it but the gold bar under it to show it is equipped is not there. Am I doing something wrong or is this a bug that I should be reporting?

Switch to a non-gatherer then switch back. Usually fixes it.