Here is a quick tutorial I made on editing multiple layers (images) in photoshop at the same time (ie. getting them all to do the same thing).
I made this immediately after teaching myself. I was excited because I actually thought of being efficient and was resourceful in going to Google (instead of playing it safe, thinking – I already know how to do each one individually so I will just do that). I was so exited I wanted to share my knowledge with others in an accessible, visual, quick way!