Hi Duane,
Thank you for writing in, on the Row or Grid configuration you will see layout options, which you can configure to have a different layout on different screen size.
Sometimes, using the layout options won’t be enough to what you might try to do, in this case, try to utilize the Hide During Breakpoints options.
On the Content Builder or Header/Footer Builder you will see the Responsive Preview options, so you can preview your layout on different screen sizes and edit it accordingly.
Additional documentation that might help you:
Hope it helps,
Cheers!