What´s it all about?
PDF files can dynamically change their content while opened. These are triggered by „actions“. The PDF/X standard demands that the display of a pdf is always the same. Therefore active components are not allowed. The only exception being elements to control the page navigation.
What can I do?
For the most part a zoom factor is saved in the display. Open your pdf within Adobe Acrobat. Click at the top left on „File“ and then „Eigenschaften“. In the new window click on „View when oppening“. Now you set all boxes as you see them in the screenshot below.
Through PDF optimizing in Acrobat you can also remove „actions“, should the method above not work.