When you add a new e-mail account to your Microsoft Outlook profile, all of the subfolders in your mailbox are displayed in a list on the left side of the window. By default, these personal e-mail folders are arranged in alphabetical order and Outlook does not allow you to manually sort or organise them. However, you can force Outlook to sort your personal folders by adjusting the folder names using numbers and symbols.
Launch the Microsoft Outlook application on your PC computer.
Go to the "Mail" tab in the lower-left corner of the main Outlook window.
Click on the plus sign next to the name of your e-mail account on the left side of the window to expand the list of personal subfolders.
Right-click on the personal folder that you want to appear at the top of the list and choose "Rename" from the contextual menu.
Add an underscore character (_) to the front of the folder's name and hit "Enter" to save the settings. The folder will automatically move to the top of the list.
Rename each of the other folders in your e-mail account and add numbers to the front of the folder names, starting with 1. Outlook will automatically sort the folder list based on numeric order. If you have a folder with an underscore symbol at the beginning of its name, it will remain at the top of the list above all numbered folders.