There is no documentation for CB Replacer Bot.

I need to know how to change the profile page header name from the defaulted formatted name to a specific new field please.

You don't need CB Replacer Bot to do that. Simply edit the "User Profile Page Title" tab in CB > Tab Management and adjust "User Profile Title text" to whatever you like; that parameter supports substitutions. If you mean the browser tab title then edit your CB menu item in Joomla menu manager and adjust "Browser Page Title" under "Page Display" to whatever you like as we will pass it through substitutions on output. Note that it will substitute based off the viewing user so you need to use user="#displayed" in your substitutions.

If you've no use for CB Replacer Bot having read the above see the below regarding requesting a refund.

www.joomlapolis.com/warranty

So how am I supposed to know how to use the plugin if there is no documentation???

Edit "Content - Community Builder Replacer" within Extensions > Plugins then begin adding your replacements there. The replace parameters have descriptions describing what they do. The product page below shows a replacement example as well.

www.joomlapolis.com/addons/cb-replacer-bot