If it is your first gallery then all your photos are published by default. You can change this auto-approval setting by clicking the "Auto approve" button on the gallery page:

You can choose whether to publish your posts automatically or manually.

What is the difference between the 'Auto-approve' and 'Manual publish' options?

The 'Auto-approve' option - automatically publishes all updated posts from your Instagram account.

While using the 'Manual publish' option - you can choose photos that you would like to display in your gallery.

How to manually publish photos?

By following the steps below you can moderate photos in your gallery:

1. Go to the dashboard and open the gallery.

2. Browse photos and click on the "Checkmark" button on a selected photo, in order to hide it or to show it. 

• The green tick indicates a published photo.
• The grey tick indicates an unpublished one.

That is it! Hope it was helpful. 😊