Preset buttons are the buttons labeled 1 - 2 - 3 - 4 .... and they're used to have four different setting groups that you can just push the button and switch from say Forward mode to Downscan mode without having to go into the menu and manually change the settings. (but you'll need a manual handy to show you how to set the preset buttons)

Yes, you can change or experiment with the settings without the transducer being in the water. You turn the unit on and disable sonar transmit (so the transducer stops trying to send a signal, which can overheat and damage the system), then go into Simulator mode to change the settings around until you find what you're looking for.

My Livescope setup doesn't have Perspective mode, so I may be guessing here ... but, if you had the depth adjustment on the right side of the screen, try putting the unit back into Perspective mode & see if it returns. As it is now, you're in Downscan mode & the depth adjustment buttons are at the bottom of your screen (- 30ft + ) just above the Nav Info button.