Open your Slideshow and click the pencil symbol to edit.

If the button at the top shows a small version of the visualisation, you need to click it to switch to the Slideshow settings.

Select "Slideshow" to be able to edit the Slideshow layout.

Click here to open the Layout Editor.

Find the Navigation Element in your Layout. It's either in the Header or in the Footer. In this case it's in the Header of the Slideshow and we want to move it to the Footer. Click the Navigation.

Drag the Navigation to the Footer.

Don't forget to save your changes.

You have successfully moved the slideshow buttons.