How does one change the encrypt local backup password to something new, without having the old password?

Thanks, tts, for chiming in, trying to help. That page you referenced has very simple directions for people using iOS 11 or above (I'm in that category):

iOS 11 or later

Removing an unwanted backup encryption setting has become easier under iOS 11 and later versions. See Turn off backup encryption for details. Your device needs to be working and able to backup to iCloud, or you need to be prepared to reset all settings on the device.

That "turn off backup encryption link" is actually the same linked I originally referenced, https://support.apple.com/en-us/HT205220. The instructions there do not work. Here is what that page says...

If you can’t remember the password for your encrypted backup

You can’t restore an encrypted backup without its

password. With iOS 11 or later or iPadOS, you can make a new encrypted

backup of your device by resetting the password.

1. 1. On your device, go to Settings > General > Transfer or Reset [Device] > Reset.
   2. Tap Reset Network Settings and enter your device passcode.
   3. Follow the steps to reset your settings. This won't affect your user data or passwords, but it will reset settings like display brightness, Home Screen layout, and wallpaper. It also removes your encrypted backup password.
   4. Connect your device to the Finder or iTunes again and create a new encrypted backup using the steps above.

You won't be able to use previous encrypted backups, but you can use

the Finder or iTunes to back up your current data and set a new backup

password.

The problem is the bolded portion of Step 3. After performing the steps up to that point, the encrypted backup password is NOT removed. Connecting the device again via USB, opening iTunes, and navigating to the backup interface, the checkbox "Encrypt local backup" remains checked. Sure, I can create new backups, encrypted with some password I don't know, but I cannot restore those backups. I can also not uncheck the box, because clicking on that prompts me for the current password. I also cannot use the "Change Password" button, because that also prompts me for the existing password.

These instructions do not work.

Encrypting a backup stored on a computer, using a password stored on the device being backed up -- which of course is not working in the case of needing to restore said backup to a new device -- makes no sense to me. That said, if that password is going to be stored on the device, assuming in the iCloud keychain, then there should be an interface to change that password on the device itself, if not "see" it like all the other iCloud keychain passwords. In absence of that, the iTunes interface should allow for setting a new password for new backups. The existing instructions imply that's the case in between Steps 3 and 4, but the instructions don't work.

Thanks, tt2. I actually tried backing up to iCloud, and that failed on multiple attempts, as well. The message it gave was that I wasn't connected to WiFi (although I certainly was, verified in between attempts). I might speculate that perhaps I didn't have enough iCloud space to store the backup? I'm not (yet?) paying for the iCloud increased space (frankly, I don't trust Apple's competence). Granted, I was attempting this from the iPhone itself, not iTunes, so maybe there would be potential there.

I suppose at this point, I am giving up. In my particular case, I am in the process of upgrading from the iPhone X to the iPhone 13. I've gotten all the photos and videos off my old phone at this point (PLENTY of frustration in that process, as well), all my music is not from Apple and thus saved elsewhere, and all my other app data and iPhone settings are transferred directly from one phone to the other. So I'll simply connect this new phone to iTunes, back it up as if it were a new phone (which it is) with a new encryption password, and go from there. EZPZ.

Much of that would not be possible if I had lost or destroyed my old phone, so I pity those reading this thread who have lost or destroyed their old device, or are hoping to proactively protect themselves from such a future incident. I suppose in the grand scheme, Apple suffers from increased cost of customer support, a damaged brand, and frustrated / distrusting customers. I certainly know that I will rely less on the Apple ecosystem in the future.

Thanks, Sean, but did you read what I wrote in the OP: "I went to https://support.apple.com/en-us/HT205220 and followed the steps under "If you can’t remember the password for your encrypted backup" and found that ..." That is the very link you pointed me to, and the section of the page I referenced. It doesn't work.

Since writing the OP, I've searched this community, and there are many examples of this same problem. The only valid answers I have found are some form of reseting the phone completely to factory settings, erasing everything on the phone, then setting the phone up as a completely new device in iTunes. That completely misses the point of backing up the existing phone data.

Is there any workaround for this that results in the ability to actually back the data on the phone up? You know, without deleting that data first?