By default, Adobe Acrobat DC updates itself automatically whenever new updates are detected. If automatic updates are disabled, however, use Adobe Acrobat's manual updater to check for new updates or use the Preferences window to re-enable automatic updates.
Check for Updates
Open the Help menu and then click Check for Updates. If updates are detected, click Download to install the updates. If no new updates are available, click Close.
Acrobat Reader DC also features a Check for Updates option on the Help menu that lets you manually check for new updates.
Enable Automatic Updates
Open the Edit menu and then click Preferences.
Click the Updater side-tab on the left pane. Check the box next to Automatically Install Updates and then click OK.
Automatic updates are forced in Acrobat Reader DC, with no option to turn them on or off. Earlier versions such as Adobe Reader 11, however, feature an Updater option on the Preferences window that lets you turn on automatic updates.