Hi, @cosmin-hurba . Your screenshot shows that you’re two clicks away from solving your problem. Or am I misunderstanding?
If you click ‘Change Grid Layout’ you’ll get this dialog:
On this dialog, click ‘Advanced Mode’ and you’ll get this screen:
Here you can click on any of the column headers (showing 300px in my example) and reset the column width for that column in the current (and all smaller) breakpoint.