You are able to determine what size you want your images to display and also select how wide you would like these images spaced.
To access these options:
1. Head over to your Photos > Galleries page
2. Use Quick Actions to select Settings on the gallery you want to update
3. Choose the Layout section
4. Use the radio dials to make your size and spacing selections
5. Be sure to save your Settings!
*Don't forget! If you want to use these settings on galleries you upload moving forward. You will want to update this within your gallery preset(s). Read more about using your presets here.