Menu font very small

Set screen DPI to real value: 52 in KDE Plasma 5.10 for FullHD monitor 42". Font in LibreOffice menus and dialogs become VERY VERY small. How to increase it?

Also think need to add support for low or high dpi monitors to LibreOffice.

  1. removed libreoffice-kde package - works ugly even under KDE
  2. installed libreoffice-gtk3 package - works fine now

Well. I worked with Libreoffice and Lubuntu 16.04.3 LTS, LXDE OpenBox. But I had to do a few more things:
a) switch off all instances of Libreoffice on all desktops
b) Run again OpenBox configuration manager (obconf on a command line) once again a reset couple of setting. (I do not know why. Probably system upgrade or so???)