Account Owners have the ability to enable, disable or update their Authorize.net settings within Store Manager.
Clients must have an Authorize.net Payment Gateway account in order to successfully enable their account.
You will find the settings in Store Manager > Website > Setup > Authorize.net.
The Merchant Login and Transaction Key are found in Authorize.net > Settings > API Transaction Key. You must know the answer to your secret question in order to obtain your Transaction Key.
After answering your Security Question, the new transaction key will be created and displayed. Your API Login ID does not change.
Copy and paste the new key into the field(s) in Store Manager.
Save your changes. You should IMMEDIATELY place a test order on your site to verify the new settings work.
If your card is declined, check the Declined Checkouts report in the Orders menu for the reason code; it will likely be a simple copy and paste error.
In addition to changing or updating your Login ID and Transaction Keys you can also disable Credit Card Processing completely. Simply uncheck the Live option and save.
Disabling Authorize.net will disable Credit Card Processing at checkout and during Order Fulfillment. All orders will have to be manually run charged via another means; an in-store swipe terminal or thru Authorize.net's virtual terminal.