Verna, yes you do have to select your font color every time, just as you would the italic or bold feature. When you go to post, along the top of the writing field you'll see a bunch of little boxes (bold, italic, underline, etc.) ending with the last box "Font colour." Click on that to find a bunch of colored boxes to choose from.
Then highlight your entry to adjust your entry as you please. I first click on the B for bold, because I think it makes the colors easier to read. Then click the color you want. You may have to trial-and-error to find the color you like best.
So, this would be how your final message would look (minus the spaces, which I added so you could see my "original").
[color=#BF00BF] [ b ] Howdy! [/b] [ /color ]