How to Comment When you are The Administrator of a Page:
There is a setting that can be changed which allows you to comment as an individual, instead of as the page. To do so follow these steps;
Under the page you do not wish to edit as (eg Company); Go to Edit Page > Your Settings > Posting Preferences, then uncheck the option for Posting Preferences.
Now you should be able to edit on the page as your individual (personal) account.
To change back; (reversal) re-check the option for Posting Preferences.