On screen

On screen
 

-Some actors never watch themselves on screen.

ON SCREEN means films/movies or television in general; but could we use the same phrase to mean the flat surface at the front of a television, computer, or other electronic device, on which you see pictures or information?

eg I see many pictures on screen, so I close the browser.

On-screen or onscreen (never two words)

Here is a link that'll answer your question.

Thank you~

Do you mean even for 'films/movies or television in general', we still can't write the words separate?

On-screen or onscreen is an adjective or an adverb, so must be used where these roles make sense, as in both of your examples.

Separated words should not be used. 'On a/the screen' is acceptable usage, but doesn't have the same meaning as 'on-screen'.

Thank you~

You're welcome.