Choose a screen size in QuickTime Player on Mac
You can set a movie to play at the size that best fits how you want to watch it.
In the QuickTime Player app on your Mac, open a video or audio file.
Choose one of the following size options:
Enter Full Screen view: Choose View > Enter Full Screen. The movie is displayed as large as possible and the menu bars are not visible. To exit full-screen view, press the Esc (Escape) key.
You can also move the pointer to the green button in the top-left corner of the window, then choose Enter Full Screen from the menu that appears, or click . To leave the full-screen view, press the Esc (Escape) key. See Use apps in full screen and Use apps in Split View.
Actual Size view: Choose View > Actual Size. The movie is displayed at its source size (not zoomed in or out.
Fit to Screen view: Choose Window > Fit to Screen. The movie is scaled to fit your screen.
Fill Screen view (only in full-screen view): Choose Window > Fill Screen. The movie is scaled and cropped to completely fill your screen in at least one dimension. This can eliminate black areas on the top (letter boxing) or side (pillar boxing), but may hide or distort the content.
Panoramic view (only in full-screen view): Choose Window > Panoramic. The movie is scaled to fit your screen, and the outer horizontal edges are compressed to avoid cropping the image.
To increase or decrease the movie window size from any size option (except full-screen view), choose Window > Increase Size or Window > Decrease Size.
If you want the file you’re playing to appear in front of all other onscreen windows, choose View > Float on Top so a checkmark appears next to it. Choose it again to turn it off.