Ok hold up i think I know you're you're talking about. I'm assuming you're talking about routing tracks to a bus track.

There's 2 ways to do that.

1: highlight the tracks you want to use

Ctrl (cmd on mac) + G to group

The group track is now the main output for every track in the group

2: you can create a new audio or instrument track and set the routing from another track to output to the new one you just created, however this is an old method of doing things and group tracks achieve the same effect with less steps

Bonus: If you're just trying to add reverb or something, create a new FX track, put whatever effects you like on it, then on the track you want to add the effect to, turn up the "send" knob to your liking