When I open a new window and then search in this 2nd window, focus returns to
the 1st window after searching, meaning I have to then switch back to the 2nd
window in order to see my search results.
There are a couple of possibilities.
This may be due to the scope of your search.
Use Ctrl+F1 to open the task pane, if it's not already open.
Use the dropdown to go to the Page List task pane.
Near the bottom of the task pane is a small dropdown labelled Search.
Use that to alter the scope of search in OneNote.
No, it's not the most obvious or convenient place to put the setting.
A wish to put it somewhere more visible and convenient has been
expressed quite a few times.
The other possibility is that simply the 2nd page didn't contain a
match for your search but the 1st page did. You asked OneNote to
search and it has taken you to where there is a result.
Andrew Watt
MVP - InfoPath