Try changing the Image width setting of the section to Half width of column, that should give you 4 per row. You only get 3 in a row for up to 3 columns. Over 4 columns and you either get 2 or 4 per row, depending on the Image width setting.
*Make sure you save your theme duplicate your theme!!! *
in the multicolumn liquid file click it and look for the
in this code you will see where it says grid–2-col if you change it to grid–4-col it should change the layout to 4 columns. same thing if you ad 5,6 ..
if you meant just add a new multicolumn with 3 instead of 2 you just need to click add section and select mutlcolumn
Excellent response. This worked! However, a little more detail in EXACTLY what to change in the code would have been more beneficial. You have to replace ALL 2’s not just the one. Thx