If you want to change the setting for multiple accounts, you may use the bulk setting editor.
Here are the steps to use bulk editor mode for sending accounts.
Select specific accounts or all accounts you want to edit.
On your top-right corner, click Bulk edit settings.
The settings window will pop out. Make sure you specify all the information you want to be applied to the rest of the accounts. The Account name and Custom Tracking Domain will remain the same unless you change the value manually.
Once you are done with the changes, click Save.
Note: If you leave any of the fields empty, except Account Name and Custom Tracking Domain, the values that will be applied to all accounts will be default values.