The size selector of the Photohop tool remains below the image and cannot be adjusted without moving

@Timo28203355kkjo have a look at this thread

https://community.adobe.com/t5/photoshop-ecosystem-discussions/stamp-tool-brush-menu-appears-at-the-back-of-the-photo/m-p/14866314#M830253

When we have our canvas in a floating window, we can either drag the window away from the panel that descends when we click the disclosure triangle of the brush in the options bar, or as in my screen shot, choose Window > Arrange, and click on Consolidate All to Tabs. When we have our canvas in tabs, the drop-down panel from the options bar will be in front of the canvas.