PM - means private message. As your case may be very specific to you only it doesn't make much sense to me run through the whole procedure publicly in the forum thread. Only solution summary is valuable, but as you already continued publicly let's continue in public ;-)
I assume that you have your passwords (those you don't want to lose) on your desktop, right? If so, you can export them either to CSV or in firefox or chrome compatible format (I recommend some browser compatible format as in case of failure you can import the data at least to browser and we can then grab it from there).
Just go Avast->Settings->Passwords and there you can find the export section (at the bottom of the section - you need to scroll). This is just to make sure you won't lose anything if something bad happens.
In your case, as you haven't synchronized data yet (as you are not trusted on any device. If you turn off synchronization on the device, all data stays there. We delete only data which has already been synchronized. If you have any other device where you have passwords stored, you should do the same means turn off synchronization.
This option is available In avast->settings>passwords on mobile settings->synchronization section
Once you are at this point it means that all your devices are ready for synchronization group reset let me know and will perform a reset and post rest of instructions.
Regards,
Martin