Touch and hold any widget (right-click on Mac and Windows) to open its menu. The top line shows when it last updated, and the items below are grouped:
Edit layout: enter editing mode and drag widgets to move them. Each widget's size is set by the widget itself.
Edit parameters: change the parameters of just this widget, such as the city or stock, without affecting the others.
Delete: removes only this widget. The tool it came from stays installed. You can tap Undo within 5 seconds to bring it back.
Tap the button in the top-right corner of your dashboard, then tap Edit to rework the whole dashboard: drag widgets to move them, or select widgets and tap Delete Selected at the top. The bar at the bottom sets the layout:
Tap Done in the top-right corner to save. Tap Cancel in the top-left corner to undo everything, including order, deletions, layout and columns.
On Free, only the first 6 widgets keep updating (in dashboard order, then in order within each dashboard), so you choose which ones stay current by rearranging them. See "Free and Pro".