To properly setup the screen resolution of your Raspberry Pi running Volumio with pi-top FHD Touch Display (pi-top | Getting started with your FHD Touch Display), you need to telnet the Volumio host to get a terminal and add (or change) the userconfig.txt with the following lines:
hdmi_group=2
hdmi_mode=82
This sets the proper configuration for pi-tp FHD screeen:
Setting screen resolution for 1920x1080 HD on Pi-Top FHD Touch Screen
hdmi_group=2 → DMT resolution modes
hdmi_mode=82 → 1920x1080 60Hz 16:9
To edit the userconfig.txt file
$ sudo nano /boot/config.txt
add the lines to the file, save it and reboot
$ sudo reboot
There are more options to achieve this, Please check at: Setting the Screen Resolution of your Raspberry Pi - Pi My Life Up) (Setting the Screen Resolution of your Raspberry Pi - Pi My Life Up