I'm learning Spanish to keep up with my family (mixed origins from spain, latin america, south america, etc.) and I've noticed that I don't quite understand when the people I'm talking to prefer that I use formal or informal.
Are there any general guidelines or standards as for when one is more appropriate? Like if it's someone who is your senior or based on how close you are to each other? Or is this maybe not as big a deal these days as it might have been in the past?