Help with revised and more streamlined backup process

Whistlestop

I have a 2 bay Synology NAS box which I use for encrypted backups (Aronis True Image). My data from my PC is backed up once a month using full-differential backup process. I've used this method for a couple of years now. My 2 disks in my NAS are in RAID 1. I do not clone disks or do full disk images. It is just my data I backup.

Most of my data consists of documents, videos,pictures,audio, gns3 files. It amounts to about 1.5TB. My personal documents and pictures are stored encrypted on my NAS using Acronis. My videos and audio are not.
As well as backing upto my NAS I have an external Samsung USB 3.0 Hard drive which I manually backup to every month. This is secured using the Windows Bitlocker and I use freefilesync to check/look for file changes. The drive is stored in my house. I know it is not perfect but i'm a bit suspicious of cloud storage solutions. Am I right to be suspicious?

My wife's PC also has some data on it which is backed up but for this she uses a normal USB memory stick and backs upto it on a adhoc basis. The data amounts to about 1GB-2GB.

I would like to improve my backup method to make it faster,more secure and even more automated. To also include my wife's PC in the backup regime if possible.

can you nice people suggest a new or revised method? I'm aware that cloud storage is the way forward when it comes to off-site backups but would need to be end to end encrypted if that was the best way to go.

A disadvantage of my current backup scheme is that I am unable to access my documents on the move. For example although I can access my videos from my NAS using my android phone because things like spreadsheets and word docs are encrypted (in the acronis backup) it is not possible to view these on my phone. It is not a major issue.

thanks