StFoldex

Thanks loukash for the reply. I changed to the Masterpage section and in the Spread Setup from Single to Facing pages. This changed in the Spread Setup to the Inner and Outer margins view. This also added a white right side page to the single Master page. You can also see in the screenshot that now the Masterpage does not sit properly anymore within the margins. I then changed for the last page the values in the spread as they should be (same values as in the Master page spread setup). Unfortunately it changes the margin to the wrong side (so to speak for the right side page instead of the backside left page. So your suggestion is not a fix. Sorry.

Have you chosen the correct colour space in Affinity Photo. sRGB is different form RGBf, or Adobe RGB (1998). Apple RGB, your own Monitor RGB (etc.) colour space? RGB looks by far more bright and crispy than a printer usually can print out. This is why you can adjust your monitor to the colour space of your printer and as well your photo/image/grapphic design software to the target colour space (could be printer for print out, or web, or just to be viewed on your monitor). You have to use a colour space in your software according to the final taget you create or edit your picture for.

See my screenshot for explanation. I know that i can input for the last page the value in reverse for left and right margin. However, this is for sure not the intended way for a software like this. So, what do i have to do to make the spread setup perform correctly?

I dragged in the (thumbnail) Page View a right page to become the left page, but now the text is NOT anymore within the given spread margins. Why the heck does the text not automatically change to sit right within the page margins of the spreads? What a disaster if one has to change many pages, that would mean to re-adjust all text and other elements positions on every changed page side's position. Holy crap!