System Preferences/Username and Password

Open Users & Groups System Preferences and select your Account. Is "Allow user to administer this computer" checked?

If not, you can create a new admin user by following this guide: https://discussions.apple.com/docs/DOC-250002676

Use the new user to give your old user Admin privileges. You can then remove that new user, or keep it.

Suggest downloading the Application Etrecheck directly from a well Respected ASC Contributor. 

The application is free or paid from added features. 

Run the application with Full Disc Access ( Security & Privacy - Full Disc Access ).

It will take a Snap Shot -  both the hardware and software.

 The Report will Not Reveal Any Personal Information. 

Post back the Full Report - copy and paste - using the Additional Text Icon ( 3rd Icon to last )

We can have a look at the report for possible issues and may have possible suggestions to resolve the issues.

Any Third Party Applications that will interfere with the normal operation of the OS, alter, modify, remove or delete or attempt to do so is an invitation for disaster and may require a Reinstallation of the OS.

This includes AntiVirus, Disk Cleaners, Disk Optimizes, UnInstaller etc.

This will include CMM

The The Built in Security  is all that is required.

Is this computer Owned by you?

Is this a Work Computer with a MDM Service and Profiles installed ?