Hello,
the tool PDF Overlay (in the PDF24 Toolbox and online) has no setting for the position on the page. If the overlay page is smaller than the pages of your document, it is placed in the center of each page without scaling.
To get the logo exactly where you want it, make the overlay PDF the same page size as your documents (for example A4) and place the logo in the bottom left corner of that page. The overlay is then laid over the page 1:1 and the logo appears at that spot. This also works online: https://tools.pdf24.org/en/overlay-pdf
With the next version of PDF24 Creator, the Toolbox tool Add watermark can also use an image, with a position (for example "bottom, left") and a size in percent of the page width. That will be the easier way for a logo.
Thank you for the suggestion to choose the position in PDF Overlay, we will add it to our list.