How to update quicktime player on MacBook air to run Skype?

As a fellow user, I can assure you that Skype 8.69 runs fine on macOS Big Sur 11.2.3, and your issue is not about the version of QuickTime on this OS. As the version of QuickTime is tied to/bundled with the version macOS, it will always be up-to-date for the system software.

Please try reinstalling or re-downloading just Skype.

How do I uninstall and reinstall Skype on desktop? - Microsoft Skype Help

↳ Mac

Greetings, Carolyn_Is_Stuck!

Welcome to Apple Support Communities! If we understand correctly, you are experiencing an issue with opening the Skype app on your MacBook Air. It also looks like you want some information on how to update QuickTime on your MacBook Air. We will do all we can to help you find the answers you need.

To start, check out this link to learn more about how to use QuickTime on your Mac: QuickTime Player User Guide.

Additionally, check out this guide to make sure the Mac meets the System requirements for Spotify. If the Mac meets all the system requirements for Spotify, you may want to delete it off the Mac and download it once more from here: Download Spotify.

We hope this information helps you out.

Kind regards.