To make sure you are commenting on a post as your business and not your personal page go to the right hand side of the ‘like, comment, share’ bar, here there is a drop down menu listing all your pages as well as your private account. Simply make sure you select the page you wish to engage as. This way you can engage as your business whilst on your personal page if needed.
To switch to your business page from your private Facebook page go to ‘shortcuts’ on the left hand side and select your page.
If you would like to view all the content from the pages you’ve liked as your page in one feed then type ‘pages_feed’ at the end of your Facebook page url like so:
This is a great way of engaging as your business page exclusively.