In addition to showing or hiding one label at a time, you can manage them all at once in your Gmail settings.
Click the More button in the left pane.
Click Manage labels.
The Settings page opens directly to the Labels tab. Here you can see all of the built-in system labels, the default mail categories, and the custom labels you've created.
Click Show or Hide to show or hide a label from the list.
Click Remove or Edit to remove a label from the list or edit a label’s name.