Collections in Adobe Portfolio - Problem with photos on the collection page

Hi,

I have different collections on my porfolio, each collection with different pages.
When I click on the title of a collection I see page photos. The problem is that depending on the collection, the page photos can appear at the top of the page, or lower with a blank space. 

I would like the page photos of each collection page to be shown at the same level/height when clicking on each collection. 

How can I do that? I have checked everywhere in the menus but cannot find any adjustment tool for this.

I hope you can help me!

Thanks in advance!