Hello,
Thank you for reaching out to us.
Depending on which Gallery Type you chose, there should be an Individual link beside the Columns option where you can set the number of columns your gallery will show on specific screen widths – https://share.getcloudapp.com/Kou7q6GB.
Set the value as 1 for the mobile screen widths so only one column per row will show.
Hope this helps and let us know if we can assist you further.
Best Regards,
Karla
Thanks that is working great.