If you are using Outlook 2013 on a smaller screen, you may not want the Navigation Bar at the bottom of the window to be full size. You can easily change it to be more compact at the bottom of the folder pane.
To make the Navigation Bar compact, click the View tab.
In the Layout section, click Folder Pane and select Options from the drop-down menu.
On the Navigation Options dialog box, select the Compact Navigation check box so there is a check mark in the box. Click OK.
NOTE: You can also use this dialog box to change the number of items that are visible on the Navigation Bar (the rest are visible by clicking the … button on the bar) and to change the order in which the items are displayed.
The Navigation Bar reduces in size, to fit in the Folder pane, and the buttons are represented by icons rather than text.
You can also access the Navigation Options dialog box by clicking the … button on the Navigation Bar and selecting Navigation Options, as shown above.