Auto re-sizing of pdf preview not working in EN20 & 21

in EN X9 the size of the pdf was auto-scaled to the width of the preview pane.
In EN 20 & 21 the zoom is fixed at 100% meaning that only part of the page is visible. Even when I manually change the zoom level it will not stay like that. If I switch to another reference and then back, the zoom level is again at 100%. This is very frustrating!!! and time consuming to change the zoom over and over again for every single reference I open.
Can you please “fix it back” to the functionallity of X9.