@Kyra27808462s3ls
If you have the Rotate tool selected, then Alt+Click will set the reference point and open the dialog. If you don't want to use the dialog, skip the Alt key and just click or drag the reference point, then drag to rotate.
If you open the Rotate dialog without Alt-clicking to set the reference point, then the reference point will jump to the middle, but I don't think this part applies to what you are doing.
Jane