[Application] UseCustomUITheme=true Then, you must define a stylesheet. But the fontSize key here is largely deprecated in v4.5+. The real power comes from . Layer 3: The Custom Stylesheet (The Power Move) This is where qBittorrent transforms. The application accepts a full Qt StyleSheet (QSS)—a CSS-like language for Qt widgets. You are no longer asking for a font size; you are dictating typography to every single UI element.
This is a brute-force method. Effective, but inelegant. The first real control lies in a plain-text file you've probably never opened. On Windows, it's in %APPDATA%\qBittorrent\qBittorrent.conf ; on Linux, ~/.config/qBittorrent/qBittorrent.conf ; on macOS, ~/Library/Application Support/qBittorrent/qBittorrent.conf . qbittorrent increase font size
/* Buttons shouldn't be gigantic */ QPushButton { font-size: 12pt; padding: 4px; } Layer 3: The Custom Stylesheet (The Power Move)
At first glance, qBittorrent seems stubborn. There is no "Increase Font Size" slider in the main preferences. This absence isn't an oversight but a philosophical choice rooted in its reliance on native Qt frameworks. However, dismissing it as inflexible would be a mistake. Under the hood, qBittorrent offers four distinct layers of typographic control, ranging from the dead-simple to the surgically precise. Before hacking config files, understand that qBittorrent is a Qt-based application. It inherits its default scaling behavior from the OS environment variable QT_SCALE_FACTOR . This is a brute-force method
[Qt] styleSheet="" fontName="Segoe UI" fontSize=12 Wait. That does nothing for the main UI. The critical parameter is hidden: