I am not familiar with that brand of binoculars but manufacturers are notorious for hiding the adjustment screws. I have a pair of Nikons that are completely covered in rubber so no screws are visible at all. It is also possible that the adjustment screws are hidden internally and can only be accessed after the eyepieces are removed. This would be much more difficult to adjust
Remember higher magnification makes everything larger, including the apparent misalignment. If you collimate at the higher magnification, then check the alignment at your lower magnification you may have a better result.
are you saying the amount of zoom changes from one eyepiece to the other? adjusting the prisms won't change that. If the alignment changes when you zoom that could mean that the lenses that are moving to cause the zooming aren't moving parallel to each other. regrettably I don't know how to fix that.
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