If you have bought a new custom domain through blogger or from a third party ,you must manually set your blog into custom domain. You should make some changes in your blogger settings to redirect your blog to new custom domain.
Lets Start : ( Old Blogger Interface)
- Login to your Blogger account and go to settings .
- Go to Publishing and Click on Custom Domain
- Now it will ask for you to buy the domain through blogger,But you have already one custom domain,.So click on 'Switch to Advanced settings'
- Type your domain name on domain text box and click on the check box below to it.
Fill up the the word verification and then click on "Save settings" button.
- Save the settings .