Find the Secure Boot option and change it to Disabled. Save the changes and reboot again. We recommend keeping Secure Boot enabled unless you're sure it needs to be disabled. This article explains how ...

It sounds to me like claiming that all old Windows versions will be unbootable is an overstatement. Rather, it's most likely the case that you won't be able to boot old media when Secure Boot is ...

Acer has fixed a high-severity vulnerability affecting multiple laptop models that could enable local attackers to deactivate UEFI Secure Boot on targeted systems. The Secure Boot security feature ...

I have yet to find any mention of problems with Windows 11 if you disable secure boot after installing it. I’m assuming this would be quite a prominent matter and easy to find if there were such ...