Jeffrey,
The built in editor in Maximizer is designed to be used as part of an integrated application. It is quite old though and doesn't support most of the more modern text formatting.
You can't change the internal editor within Maximizer, however there is some basic integration to Word included with Maximizer, look in MS Word for the Maximizer Toolbar, this allows you to link in fields from the currently selected record.
If you want to perform more complex merging tasks within Word then CABC have written a utility called Max Doc that provides better integration between Word and Maximizer as well as the ability to define templates within Word and merge those templates against address book lists within Maximizer.
You can download a trial of that product from our website,
http://www.cabc.co.uk.