As with the other exporting options, you can save a snapshot of the entire account or select specific campaigns and ad groups. The backup is stored as an Ads Editor Archive (AEA) file, which you can import any time in the future. AEA files include unposted changes, comments, and draft campaigns. When you import a backup file, the parts of your account that were archived are restored to their previous state.
Export an AEA backup file
Go to the Account menu > Export > Whole account > AEA.