PayPal

Log into the business account on PayPal click profile then click your company name. 

Under selling preferences click website payment preferences. 

Choose ‘on’ for auto return and add the URL of the website. 

Click save.

In store manage under ecommerce settings choose credit card and PayPal then set the PayPal email address to be the same as the email address you used to log into PayPal.

Place order on store site and pay via PayPal, you will be redirected back to the site.

Authorize.net

Log into Authorize.net and click account. 

Under ‘transaction response settings’ click response/receipt URLs. 

Click add URL and add the URL of your site and click submit.

IN CASE YOU HAVEN’T ALREADY SET UP THE API LOGIN ID AND TRANSACTION KEY

Go to account settings. 

Click API Login ID and Transaction Key. 

Take note of the API login ID and generate a new transaction key take note of the key too. 

In store manage under ecommerce settings choose credit card and Authorize.net then add the API Login ID and Transaction key.

Place order on store site and pay via Authorize.net, you will be redirected back to the site.