The downside of using the Prezi built-in frames is that you cannot edit each frame individually, this means you cannot have multiple frame colors in one presentation. For example you would want to make your Prezi with blue frames, but in the end, you need 1 red frame and this is not achievable. While you can change the frame colors in entire Prezi then it is simply not possible to edit one specific frame. This is quite frustrating, because for the built-in shapes, Prezi allows to define 5 different colors that you can choose from.
Solution?
The solution would be to build the frame yourself using the Prezi shapes – this works with the rectangle and bracket frame, however there is no easy workaround for the circular frame! By building the frames yourself, you will have the ability to add 5 different frame colors in on Prezi via CSS. Simply duplicate the frame and use it as much as you need. Just watch the tutorial video: