ユーザーフォルダにあるqt-config.iniを編集
[Layout]の所を
custom_layout=true
custom_top_left=0
custom_top_top=0
custom_top_right=1200
custom_top_bottom=720
custom_bottom_left=1200
custom_bottom_top=240
custom_bottom_right=1840
custom_bottom_bottom=720