How do you have a chord containing different note values?

Hey there,

I want to put in a piano triad chord where I have a crotchet and a dotted Minim to fill the bar for the root note. Then have the 3rd and 5th as semi-breve's, but whenever I try to input the different values. The whole chord becomes whatever value I currently input. So I can have the whole chord as a semi-breve or something else but I can't have the root as a certain value and then the other notes as something else. But surely there is a way around this because this isn't a complicated bar that I am trying to put in.