The daily compatibility checker pop-up is not a minor inconvenience, and it is not your fault. It is a persistent failure of the software to listen to a user's explicit choice, and the fact that you have to reset it every single morning is a broken experience. You did everything right: you unchecked the box, you looked for solutions, and you even tried to convert the files. The problem is that the tool you are using is fighting you instead of working with you.
Here is what is actually happening. Your files are XLSX and XLSM formats, which are already the modern standard. The compatibility checker is designed to warn you about features that might not work in older versions of Excel, but if you are not sharing these files with someone using a legacy version, the warning is pure noise. The fact that it reappears daily, despite your explicit instruction to stop, suggests that the setting is not being saved properly, likely because of how the file is being accessed on a shared drive or because your company's policy is resetting the preference on every open. You cannot change the version, and you cannot control the build, so you are stuck in a loop where the software ignores your input and assumes you need to be reminded of something you already know.
This matters because it points to a deeper issue with how traditional spreadsheet tools treat their users. They assume you need constant hand-holding, and they prioritize hypothetical edge cases over your actual workflow. You are not asking for anything complicated. You want to open a file, do your work, and close it without being treated like a novice who might accidentally break something. The fact that this is not possible without a registry hack or a policy change you do not have access to is a sign that the tool is not designed for the way you actually work. It is designed for the way the software vendor thinks you *should* work, and that is a fundamental mismatch.
The practical takeaway is simple: stop wasting your energy trying to fix a setting that the software refuses to respect. Instead, push back on the people who control your environment. Ask your IT department why the compatibility checker is being forced on files that do not need it, and request a group policy that disables it for modern file formats. If that is not an option, then consider whether the shared drive is the culprit and test a local copy to isolate the issue. But do not accept this as normal. A tool that ignores your preferences is not a tool; it is a hurdle. And your time is too valuable to spend it clearing the same hurdle every single day.