How to adjust the "Closets module" window to be able to see the lower buttons (in the case they are not visible).

This could be due to screen resolution as this window is made to be clearly visible on 800-pixel height screens. However, you can resize the window by placing the mouse in the upper part of the window and left-click on it and drag it down to change its height. Once done that, move the window up to see the lower buttons. Click on "accept" to save changes: