In my novel I have many different story lines that are happening at the same time. If I have one scene that takes seven pages and then flips to another scene that actually happened at the same time but in a new location and with different characters, then how do I write the switch without confusing the reader?
At first: Clearly establish the character or location. The first time you show new location or POV character, clearly establish both. To do that, focus on two things: sensory details (what the character is sensing through the five senses) and opinions (what the character thinks of the things being sensed).
The character's opinions will help establish the character.
The first time, use all five senses. These will help establish the location--and to some extent the character: Of all of the available sensations, these are the ones the character is noticing.
Later: Re-establish the character or location. The next time you flip to an already established location or POV character, remind the reader by reusing some of the more telling details and opinions. Include a few new details and opinions, to help the reader see what's changed.
Later: Quickly recall the character or location. Later in the story, a quick reminder (recalling one or two evocative details) will be enough, as long as you've clearly established them earlier.