how do only change one angel

if I have the rotation 0 67 89 and I wanna change the 0 to 90 but I want the other angels to stay no matter what they are so say the angels instead are 0 45 87 then i still want to be able to change the 0 to 90 with the same bit of code how do i do that?

transform.eulerAngles = new Vector3(90, transform.eulerAngles.y, transform.eulerAngles.z)

This works by setting X to your desired new value and setting y and z to their current values.

thanks for the help