Overlay position

Hi,
I've been using the "overlay" tool to overlay a logo (I made a small pdf version of the logo) on some PDFs using PDF24 desktop version on two separate computer as well as using the online version.
I could not find a way to choose where the logo would be displayed on the pages, but what is odd is that on one of the desktop and on the online version, the logo overlay always ends up in the exact center of the page. On the other desktop, the logo ends up on the bottom left corner (this is actually what I need). How can I define where the logo/the overlay should be positionned ?

Thanks in advance for your time