qBittorrent official forums

New computer and nVidia card.  Had problems getting screen to 1920x1080 using Gnome.  All seems to be fixed except qBittorrent,  Way too large.  Had same problem with Calibre but found a setting. cannot find anyway to get qB to display in a 1920X1080 screen. 

You need some "qtconfig" tool for whatever Qt version and distro you use. Gnome is GTK, qBittorrent (And KDE) is Qt.
So you have the GTK stuff set up, but don't have a config for Qt.