Adjust the number of images displayed on a Gallery Page for the Wexley template

Site URL: http://www.kouroshsotoodeh.com

Hello there, 

Is there anyone knows how we could adjust the number of images displayed on a Gallery Page for the Wexley template?

For now mine display 3 images per row and I'm looking for a custom code to have only 2 images per row as i could see other user already have with same Wexley template (attached screen shot below)

Thanks and I'm looking forward to hear if anyone knows :)

BEST

I am using Wexley for one site https://christinegregoryphotography.com/

I have set it for two columns before, I set the gallery for index full width, adjusted the index item size until the page made two columns. Then I  adjusted the padding, the space between items. All the above is done by selecting a gallery page then going to config/design/ site styles. Click on an empty space beneath the header. Menu updates to show the tweaks you can make.