All of Text changes

[Mgmator]

Sometimes when I use the program, I can edit just single letter/word within a text box, other times the entire text box will change. This means if I want some words/letters one font and others not, I have to make space for that word in one text box and then create a separate text box for the font that's different -- making something that should take a few seconds take 10, 20, 30 minutes or more depending.

Is there some sort of setting I can change so that the entire text doesn't change?

[rich2005]

Using Gimp 2.8 ? This little video (4 minutes) might help. http://youtu.be/ChcTE9KROmc

Gimp 2.8 or Gimp 2.10 basically the same.
Use the Text tool options to change all of the text property in any text layer.
Use the on canvas text tool to select and change individual (or several) characters - size / font / colour ..etc