I choose a measure where I want the notes. I choose an eighth note from the keypad and put it in the measure. I highlight the note, press COMM + 3 and the triplet bracket comes on over the note. I then put another eighth note where the 3rd eighth note would go. I end up with an eighth note, an eighth rest and another eighth to complete the triplet. It looks fine except over the eighth rest there is a line coming down as if there was another eighth note, There technically shouldn't be a line coming down over the rest. So, I'm able to click on the bottom of the line and a little square appears which you can grab and drag up to the bracket and hide it. When you're putting in a lot of eighth note triplets, fixing this is time consuming. Hope this explains it.
And now I just check the parts to be printed out....all the editing with "those" eighth with the line coming down in my score and I saved them, well they were not saved in the parts. Either I'm doing something wrong or not. So, I either have to redo all the parts and correct the triplets, which is more time consuming, or just leave it alone. I think something is not right.