Problem with zoom in document

When I use InDesign and other adobe programs I like it when I click on <Z> for zoom and just click and drag to zoom in/out. Sometimes when I am working in a program, it almost like the program forgets how this function work... It changes the mechanism, so that when I zoom I select an area, and it zooms in to fit the screen to that area. I don't really like this way of zooming. Is there any way to fix this when I am working in a project? why is this happening?
Thanks