You can adjust the settings by clicking on the 2 sliders on the main screen at the bottom right.
To minimise GOOSE VPN you can click on the 3 bars on the main screen in the top left. There, under "Settings" you can enable the option "Minimise to system tray".
If this option is enabled, GOOSE VPN is minimised when you click on the cross.
If you minimise GOOSE VPN, it can be found in the taskbar when you right click on the arrow: