Try to always keep your shoulders down. Even when you are in fifth port de bras, they should be kept down and not scrunching upwards. Sometimes a dancer may have raised shoulders because they’re concentrating too hard on trying to be in a good position or strong port de bras. Relax and your position and port de bras will improve,
It helps to think of relaxing the top of your shoulders, but trying to pull your shoulder blades down and into each other slightly. Don’t over-do it, but just enough so they feel “tacked” in and down. By doing this, you’re able to have that “held” and strong feeling while still staying relaxed on the top. This is a very efficient use of your muscles, and that’s part of the formula for a solid technique.