@Bolly
Solved. Thank you

@MV I don't have a Volla X23, but the scaling probably works similar on most devices.
The steps in the question are maybe already the solution for you:

https://forums.ubports.com/topic/9317/how-can-i-change-scaling-on-20-04-focal-without-ut-tweak-tool-and-without-reboot

... These devices (and maybe other devices) set the scaling in /etc/deviceinfo/devices/halium.yaml. In this file I changed "GridUnit" to a more convenient value (i.e. 28 on FP3 and 18 on Lenovo). To make these changes take effect it is not sufficient to just restart Lomiri with systemctl --user restart lomiri-full-greeter.service. You'll have to reboot the device...

@Idcrafter
Multi Boot runs very well on a Volla Phone 22 - if the VOLLA OS 11.1 version of 17.10.2022 is used (was delivered with this version in October 2023).
And yes there are updates to newer versions (Volla OS 11.1 from 11.01.2023 and 16.06.2023). But I am not sure if these versions are suitable for Multi Boot. AND CAUTION: With Volla OS 12.x no Multi Boot is currently possible. Volla is working on it. For perspective see https://volla.online/en/blog/files/november-update-23.html.
The additional operating systems are stored on an SD card with an (automatically generated) boot manager. The SD cards can be changed (and therefore also copied) without any disadvantages. Volla OS accesses the boot manager of the SD card and starts the additional operating systems from the SD card.
The installation of Volla OS 11.1 is possible with UBports. Stand-alone installations such as Ubuntu Touch are overwritten. When installing Volla OS with UBports, all initializations and user data will be lost!

I'm going to be paranoid 😄 Maybe the crazy Volla is due to its takeover because of the newly discovered security issues ? cf new OTA-7 coming soon.

@mardy Same here, I don't know when it will be solved for RN7.
Also noticed that online charging works, but no charge indicator on the display....

Is it possible this is not a device bug but rather an OS quirk? If you are in an app using audio and press the volume buttons they control the volume for that app type. If you press the volume keys while nothing is running it adjusts the ring volume (at least it seems to on my oneplus one). Now for the real quirk, the buttons still adjust the volume while the phone is asleep. To test this turn the volume all the way down, press the power button to put it to sleep then press the volume up ten times followed by the power button. You will see the on-screen volume level and it will be up. If it is not on-screen press the volume button one more time to bring it up and see if the volume was adjusted while the phone was asleep. So it may be the volume is being turned down by the buttons while in your pocket.

@domubpkm Yes, you are right. On Aquaris I used the File Manager to find the contact.db.
And I'm an 'idiot' 😁
I forgot to set visible all file in the Volla Phone Directory. Now I see it
Thanks again

@mv if the Italian translation is not intuitive/good enough, you can improve it at https://translate.ubports.com/

@mv Hi.
For me, BQ AQUARIS E5 HD is a very good phone and very STABLE with 15.04 Ubuntu Touch Ubports OTA 3 Vivid : everything goes virtually good except little bugs.

So, as you have flashed your phone with 16.04 UT, can you say what's going well and what's going wrong presently in daily usage ?

Especially, are WIFI and HOTSPOT work smoothly on this now Xenial phone or no ?
I'm a user and i wants to have a viewpoint before flashing 16.04 my BQ E5 HD, now or much later.

Thanks very much.

I have updated my E5 to UBPorts using the magic device tool and all went fine. The os is good on my phone and I like it so much I have moved my M10 over too. I have moved a friends OnePlus One and this works good too. I wooed suggest you go for it.