I´m using qgis 3.16 and have the folowing Problem: If i´m in the primary Window the scale on the bottom of the scrren shows me a correct value, but if i switch into the Printlayout mode the value of scale is wrong and about 10 times higher. I added to my project a shapefile and a few maps to work with. So far i didn´t tryed anything because i´m quite lost. I read in another article that it might help to change the CRS, but i have no idea where to do it. How to fix the wrong scale?
In the picture you can see the scale bar shows 3750km which is wrong, it must be about 700 meters.