Hi jaso143
welcome to the Apple (user-to-user) Community!
Re: Application : Buttons in the MacBook is unresponsive
Wondering which MacBook model, which MacOS version, and which browser you are using.
(Keeping the MacOS updated to the newest compatible MacOS version often improves difficulties.
You can check for updates in System Settings (or Preferences) > General > Software Updates.)
It is also unclear whether the website, eigibility, upload, and application issues are Apple-related.
Eg:
Some websites are tailored for specific browsers, and do not perform as well with other browsers.
(Depends on the website-developer's ability to ensure whether their site functions in all browsers.)
Often you can find the preferred browser info., in the help / support pages on the particular website.
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Re: "The application page frequently crashes"
If Safari browser is in use:
See: If Safari doesn't open a page or work as expected on your Mac - Apple Support
Eg: says: "Check VPN or other security software:
If you installed VPN or other software that monitors or interacts with your network connections, that software could affect your use of the website or the internet. Learn about network issues related to VPN and other software. "
Unnecessary third-party (non-Apple) apps like ad-blockers, virus checkers, cleaners and the like often cause issues. Try turning them off or use uninstallers from their developers.
Any necessary third-party apps need to be kept up-to-date to remain compatible.
All the best :-)