1.Open the notebook you want to move in OneNote.
2.Click File > Export > Notebook > OneNote Package and Export this notebook.
3. Send exported file to account B.
4. Sign in OneNote with your account B, go File > Open. Browse the location where the exported file is saved (make sure you change the file type to OneNote Single File Package as highlighted below):
6. On the Unpack Notebook screen, give the notebook a Name and browse a location where you want the imported Notebook to be saved.