New Hunter Pet Training - I'm consfused

It looks like most of the youtubes I watch are no longer correct for pet training (is that right)?

I can't open any special windows for my hunter pets, or see any way to train them. About all I notice is under the pet name they have the abilities of the pet.

Is there any way to change or improve a pet? Do I still need to tame different pets to learn their abilities, and then somehow pass those on to my main pets? (Because if so I don't see how to do it).

I also read that at level 24 the pets get some boosts in their level and strength - is that gone too? Because I just turned 24 and see nothing different.

Any tips to clear this up for me would be really appreciated.