OneNote 2016 doesn't automatically organize or alphabetize section or page tabs. You can keep your notebooks organized by arranging your section tabs and page tabs in a way that is meaningful to you.
Rearrange section tabs
Section tabs run across the top of your notebook and are a great way to organize your content by topic or subject area. You can change the order of sections anytime.
In the row of sections near the top of the page, drag a tab left or right until it's in the position where you want it.
A small arrow will appear in the spaces between other sections as you move the mouse, so you’ll know where the tab will end up when you release the mouse button.
Tip: If you make a mistake, press Ctrl+Z to undo your changes and try again.
You can add new sections and create section groups to help you stay organized. Section groups let you combine sections into a group of their own, so it's easier to navigate through section tabs in large notebooks.
Rearrange page tabs
Page tabs run down the side of your notebook and are a helpful way to organize content in a section.
In the page tabs column along the side, drag a page tab up or down until it's in the position where you want it.
A horizontal bar will appear in the spaces between other pages as you move the mouse so you’ll know where the tab will end up when you release the mouse button.
Note: To rename a page tab or section tab, right-click the tab, and choose Rename.