Can I change the photos that show on the Calendar layout when using them in a Photo Book?

The photos that are shown in the Calendar layout when creating your photo book come directly from your journal. In other words, any Calendar pages you choose to display in your book will be the same as what you'd see when logging into Tinybeans.

If you want to change which photo is shown on a day in the Calendar for your photo book, you need to change the pinned photo for that date through your journal itself. Go to your Calendar in your journal, find the photo you'd like to display for the given date, tap the 3 dots beneath the photo and select "Pin as day photo". Then, return to your photo book draft and re-select that Calendar month for the desired page so that it refreshes. The newly pinned photo should display.