Illustrator in portrait

[Jo29974413yefo]

How do I switch illustrator to portrait mode on windows?

[pixxxelschubser]

For new documents in the dialogue box for new files.
For existing documents:

Have you already tried the artboard tool [Shift]+[O] ?

[tromboniator]

[Monika Gause]

You want to rotate your Microsoft Surface (or other tablet device)? That is not possible.