Axis 4,5 and 6 won't move in reduced speed in Automatic Mode

I’m an Automation and Robotics Technician intern with DuROCK Alfacing International Limited. I’m working with ABB IRB6640 M2004 robot
I programmed the robot to depalletize bundles stacked on a skid to a conveyor line. When I switch the robot to Automatic Mode and reduce the speed to 50% , axes 1, 2 and 3 move at the reduced speed but axes 4,5 and 6 still move at 100% speed and not the reduced speed. For the purpose of our application we need all the axes to move at a 50% reduced speed. Any suggestion to what I should to achieve that ?
Thank you.
Comments
As Lee pointed out with any move all the axis will arrive at the same time so most of the time they will be moving at different speeds to be able to achieve that.
So to get each axis moving at approximately the same speed you will need to have each move command moving each axis approximately the same number of degrees.