@SGaist I tried the Qt 5.12.6 and it did the trick! Thanks. But interestingly, the title of the main application is no longer scaled by "Make text bigger" setting but the dockwidget ones does. I guess that there is an intention not to scale the main title. "Make everything bigger" setting does scale everything properly now except the titlebar height of only the main application looks not enough for the enlarged font size. I will give qt5.14 a try as well.