Printing size different in Layout options and Printing mode

I have set my page layout to Din A4 in Layout options but when I switch to print mode I read US letter as selected page size. Why that?

The page size you choose in Layout Options is independent from the paper size used in Print mode to actually print. This is so that you can e.g. proof an A3 score on A4 paper, or vice versa.

The paper size chosen in Print mode will normally be the default paper size supported by your printer, but it doesn’t change when you change the page size in Layout mode. Once you change it in Print mode it will remember that choice for that layout.

Ok. I see.
Can I set Din A4 to standard for all new scores in print mode? If so, how?

I believe the paper size chosen in Print mode is your printer’s default paper size, so perhaps you can set your printer’s default paper size in the OS?

No, unfortunately this is not the case. The default setting in printer setting is Din A4 but every new score in Dorico shows US letter in the printing dialogue on the right hand side.

I tried with other apps but it’s a Dorico problem. No problems with other apps.

OK, well, for the time being I’m afraid you’re stuck with having to change the paper size in Print mode once for each project before you print. I hope this doesn’t cause you undue inconvenience.