I’m not sure if I’ve changed a preference or what. When I drag with the Select or Transform tool to select more than one element, the entire screen turns red with some elements green. Any help would be appreciated. 
Could it be your onion skin that’s turned on, and it’s onion-skinning all your layers?
Can you perhaps link a screenshot? You can upload your screenshot to a free site like Photobucket and post the link here.
~Lilly