I can imagine how this could be frustrating. There are a few methods to reset the password on your Mac:
1. Restart and show password options: You'd restart your Mac and follow on-screen instructions, possibly using your Apple ID or a FileVault recovery key.
2. Reset using your Apple ID: Click on the reset option using your Apple ID, then follow the steps provided.
3. Reset using your recovery key: Utilize your FileVault recovery key to reset the password.
Each of these methods has step-by-step instructions on the official Apple Support page that could guide you through the process.
If you forgot your Mac login password - Apple Support