I'm new to SolidWorks, usually I work on Catia V5, so I'll explain my problem. When I do the drawing, it doesn't allow me to set my sheet size and scale, it does that automatically. The second problem is that the dimensions I put in my design are not the same in the drawing and I don't understand the conversion, for example I have a dimension of 12 mm which becomes 0.47mm on a 5:1 scale. When I redo the calculation to find the dimension, I can't find the 12 mm.
Right-click on the name of your sheet on the left and go to properties. You can change the format as you see fit.
0.47 corresponds to the conversion to 12mm inches. To reset to mm, go to Tools > Options > Document Properties (tab at the top) > Units.
Once that's done, I advise you to save your document as a Template. File> Save As and in the document type, you choose drawing template. That way you can start from this document with each new plan and you won't have to do the manipulation for the units anymore