Transfer app settings from old phone to new Fairphone

[AndiOnTour]

I followed the steps like described here or on google Android pages to transfer apps and settings from my old Samsung phone to the new Fairphone 4. The apps are now installed and some Android settings transferred (e.g. keyboard), but the app settings are missing. All the apps are running with default settings, not with my customizations I had on the old phone.
How can I transfer the settings / customizations from the old phone to the new phone? The old phone is Samsung S9 with all Android updates (Android 10).

[Discostu36]

I exported/imported the settings individually for each app. As far as I know, there are backup apps that can do that globally, but they need root. Others might know more about that.

[AndiOnTour]

Thanks for your hint. After resetting to factory settings and trying the transfer and waiting for some time, and doing this resetting and retrying multiple times, I finally got settings of apps restored. Not clear to me what made it work. And as you already said some apps need special treating (like WhatsApp).
So the issue seems to be solved “by xmas magic”