Hello,
Sorry for a delay.
On your Grid settings panel there is an option on how many columns will show on what device:
http://storage8.static.itmages.com/i/16/1020/h_1476986220_5883322_0b730c5808.jpeg
And keep an eye on the Max Visible Rows that will limit how many items will show:
http://prntscr.com/c950bk
Basically, its the number of columns multiply by the Visible Rows.
Best regards,
Jack Richardson.