Hey Gil,
Yes you can, to change the Maximum number of columns you will need to edit a few lines of the Plugins .php Scripts. You can access these files either through an FTP Client (e.g. Filezilla) or a WordPress plugin (e.g. WP File Manager)
SETTING THE TOTAL MAXIMUM NUMBER OF COLUMNS
This line you need to edit is located in ‘class-frontend.php’ at line 613, simply change the Max value to whatever you want (the current default is set to 12).
public_html\wp-content\plugins\responsive-lightbox\includes\ class-frontend.php
Line 613: ‘max’ => 12
SETTING THE MAXIMUM NUMBER OF COLUMNS FOR EACH INDIVIDUAL SCREEN WIDTH
there are 8 max values to change here, personally I’d just set all the max values here to be the same as what you’ve set above.
public_html\wp-content\plugins\responsive-lightbox\includes\class-settings.php
Line 516: ‘max’ => 6,
Line 522: ‘max’ => 6,
Line 528: ‘max’ => 6,
Line 534: ‘max’ => 6,
Line 792: ‘max’ => 6,
Line 799: ‘max’ => 6,
Line 806: ‘max’ => 6,
Line 813: ‘max’ => 6,
Just save your edits or re-upload the files depending on how your editing them and that is it, you’ll be able to set your galleries to your new max values.