"apple+ctrl+r" also increases the oversampling factor. I also tried "ctrl+shift+r", which actually turned on/off the disk recording of image, as if it's normal "ctrl+r". So in my terminal:
"r" = "alt+r" = "ctrl+r" = "apple+ctrl+r": changes the oversampling factor, like normal "alt+r"
"ctrl+shift+r": record the current image directly to the disk (./SUMA_Recordings), like normal "ctrl+r"
"shift+r" (="R"): toggle continuous recording, like normal "shift+r"
Strange. At least it doesn't look like AFNI/SUMA problem, but more like setting in my terminal or virtual machine.. Anyway, thanks a lot for your help with troubleshooting this issue!