Changing the colour of a selected piece of text

Hi

This is not a hugely serious problem, and you may not get what I mean, but when I am trying to change the colour of certain text within a text box (not the entire paragraph) it proves very difficult.

It is not impossible, I can do it, but not very easily, then when I do, it often changes the text back to black again a few moment's later.

I have created a short video to show you what I mean.

This can be viewed here.

http://www.screencast.com/t/YxrKVbnQ

Please let me know.

Thanks