Resetting Network Settings does NOT reset the encrypted backup’s password. It just resets the Wi-Fi and Cellular Network settings.
Looks like you have created an encrypted backup of your iPhone on your computer. You have stated that you have forgotten the password.
There is nothing that you can do to change the password of that encrypted backup file. You will get unlimited guesses to enter the right password. If you cannot guess it, then forget that backup file.
I recommend that you create another backup of your iPhone and restore from the new backup. You can do this by deleting the encrypted backup first and then start a fresh backup. You can choose MANAGE BACKUPS when connected to a computer and then RIGHT CLICK on the backup file and choose DELETE. Once the old encrypted backup file is deleted then create another backup file and use it to restore your new iPhone from. More information below:
Transfer Data from old iPhone to new-
Do you have a backup created either on iCloud or on your computer?
Method 1 - Backup your old iPhone on your computer like this 👉 How to back up your iPhone, iPad, and iPod touch - Apple Support and then Restore your new iPhone from that backup like this 👉Restore your iPhone, iPad, or iPod touch from a backup - Apple Support
Method 2 - The Quick Start method and here is how to do that 👉 Use Quick Start to transfer data from your previous iOS device to your new iPhone, iPad, or iPod touch - Apple Support
Axel F.