Knowledgebase
How to disable and enable the customer login redirect in Magento
By default, when a customer logs in to their account on your Magento site they are automatically redirected to the dashboard of their account. The dashboard is the page on the frontend from which they can manage their account settings, view order information, etc. If you want to, you can disable this redirect. In this case after the customer logs in to their account they will not be redirected to the dashboard. They will be on the same page from which they logged in (e.g. a product details page, a category page, etc.). Of course, they can go to their account's dashboard by clicking on the My Account link that's on every page on the frontend of your site.
To disable/enable login redirects, in the admin panel of your Magento go to System menu>Configuration>Customer Configuration button in the Customers section on the left>Login Options panel on the right. Expand the Login Options panel by clicking on it and you'll see a drop-down menu labeled Redirect Customer to Account Dashboard After Logging in. Set the drop-down menu to No or Yes to respectively disable or enable the redirect. Then click on the Save Config button in the upper right corner.