Stop toggle between zoom in and zoom out in Camera Raw?

The default setting for my cursor in reviewing images in Camera Raw was to zoom in on every click, centered on where my cursor is in the image.  Now I get a Zoom in on the first click, but then it zooms back out, so I have to use key commands to get my desired zoom.  I do a lot of macro photography where I need to blow up one area in a burst-modes series of images to quickly determine which one has the desired element in sharpest focus.  I do not want to set a single zoom setting for toggling back and forth because different images differ in what zoom is needed.  How can I recreate this desired behavior?