To change the layout of a text & image widget/text & image item you need to enter the enter the item's edit mode. In order to enter the widget's edit mode click on the pencil icon ,while hovering over the widget. Then, the widget opens on the Layout tab. Choose your desired item structure/ item layout.
In every text & image widget you can change the layout of the widget. EXAI allows you to have 13 scenarios for an item's layout.