Resolution and scaling issues on dual monitor with nvidia (one 4k HiDPI, one VGA with converter)

I am trying Kubuntu 18.10 and I have a nvidia GTX 1060 (driver 418), a LG 27" 4k monitor (27UD58-B ) and an older HP 22" 1680x1050 monitor (HPw2207) with a VGA cord and a VGA-> DP converter. My issues are as follow: 1) I can't get my vga screen with converter to use a resolution above 1280*1024 2) I'd like to use screen scaling because everything is so damn small on the 4k display. I'd want the scaling to only be done on the high-dpi display if possible. **Current setup:** I am using Nvidia drivers 418.56. $ nvidia-smi Mon Apr 15 15:07:47 2019 +-----------------------------------------------------------------------------+ | NVIDIA-SMI 418.56 Driver Version: 418.56 CUDA Version: 10.1 | |-------------------------------+----------------------+----------------------+ | GPU Name Persistence-M| Bus-Id Disp.A | Volatile Uncorr. ECC | | Fan Temp Perf Pwr:Usage/Cap| Memory-Usage | GPU-Util Compute M. | |===============================+======================+======================| | 0 GeForce GTX 106... Off | 00000000:23:00.0 On | N/A | | 10% 64C P0 25W / 120W | 739MiB / 6076MiB | 3% Default | +-------------------------------+----------------------+----------------------+ +-----------------------------------------------------------------------------+ | Processes: GPU Memory | | GPU PID Type Process name Usage | |=============================================================================| | 0 958 G /usr/lib/xorg/Xorg 386MiB | | 0 1413 G /usr/bin/kwin_x11 192MiB | | 0 1432 G /usr/bin/krunner 1MiB | | 0 1434 G /usr/bin/plasmashell 111MiB | | 0 1509 G /usr/bin/latte-dock 29MiB | | 0 9387 G /usr/lib/firefox/firefox 1MiB | +-----------------------------------------------------------------------------+ and normal higher resolutions are not available: $ xrandr Screen 0: minimum 8 x 8, current 4864 x 2160, maximum 32767 x 32767 DVI-D-0 disconnected (normal left inverted right x axis y axis) HDMI-0 disconnected (normal left inverted right x axis y axis) DP-0 connected primary 3840x2160+0+0 (normal left inverted right x axis y axis) 600mm x 340mm 3840x2160 60.00*+ 30.00 2560x1440 59.95 1920x1080 60.00 59.94 1600x900 60.00 1280x1024 60.02 1280x800 59.81 1280x720 60.00 59.94 1152x864 59.96 1024x768 60.00 800x600 60.32 720x480 59.94 640x480 59.94 59.93 DP-1 disconnected (normal left inverted right x axis y axis) DP-2 disconnected (normal left inverted right x axis y axis) DP-3 disconnected (normal left inverted right x axis y axis) DP-4 connected 1024x1280+3840+832 left (normal left inverted right x axis y axis) 376mm x 301mm 1280x1024 60.02*+ 1280x960 60.00 1152x864 75.00 1024x768 85.00 75.03 70.07 60.00 800x600 85.06 75.00 72.19 640x480 85.01 59.94 DP-5 disconnected (normal left inverted right x axis y axis) **First issue: fixing resolution** I have tried to "addmode" using xrandr, but I get a BadMatch error. This is apparently normal with nvidia video cards. $ cvt 1680 1050 60 # 1680x1050 59.95 Hz (CVT 1.76MA) hsync: 65.29 kHz; pclk: 146.25 MHz Modeline "1680x1050_60.00" 146.25 1680 1784 1960 2240 1050 1053 1059 1089 -hsync +vsync $ xrandr --newmode "1680x1050_60.00" 146.25 1680 1784 1960 2240 1050 1053 1059 1089 -hsync +vsync $ xrandr --addmode DP-4 1680x1050_60.00 X Error of failed request: BadMatch (invalid parameter attributes) Major opcode of failed request: 140 (RANDR) Minor opcode of failed request: 18 (RRAddOutputMode) Serial number of failed request: 45 Current serial number in output stream: 46 My /etc/X11/xorg.conf file has been generated by nvidia usind sudo nvidia-xconfig : $ sudo nvidia-xconfig Using X configuration file: "/etc/X11/xorg.conf". Backed up file '/etc/X11/xorg.conf' as '/etc/X11/xorg.conf.backup' New X configuration file written to '/etc/X11/xorg.conf' The xorg.conf only contains one monitor, is this normal. I have tried to add a "Modeline" line under the Monitor0, but it didnt change anything. # nvidia-xconfig: X configuration file generated by nvidia-xconfig # nvidia-xconfig: version 418.56 Section "ServerLayout" Identifier "Layout0" Screen 0 "Screen0" 0 0 InputDevice "Keyboard0" "CoreKeyboard" InputDevice "Mouse0" "CorePointer" EndSection Section "Files" EndSection Section "InputDevice" # generated from default Identifier "Mouse0" Driver "mouse" Option "Protocol" "auto" Option "Device" "/dev/psaux" Option "Emulate3Buttons" "no" Option "ZAxisMapping" "4 5" EndSection Section "InputDevice" # generated from default Identifier "Keyboard0" Driver "kbd" EndSection Section "Monitor" Identifier "Monitor0" VendorName "Unknown" ModelName "Unknown" HorizSync 28.0 - 33.0 VertRefresh 43.0 - 72.0 Option "DPMS" EndSection Section "Device" Identifier "Device0" Driver "nvidia" VendorName "NVIDIA Corporation" EndSection Section "Screen" Identifier "Screen0" Device "Device0" Monitor "Monitor0" DefaultDepth 24 SubSection "Display" Depth 24 EndSubSection EndSection **Second issue : scaling** I have taken two steps to allow the HiDPI screen to display text and GUI in a more readable size: 1) System settings - fonts - Force Font DPI 144 (instead of 96) 2) system settings- display and monitors - scale display 1.5 (instead of 1). I would lke these settings to only apply to the 4k monitor, is this possible at all?