1 – First go to Extensions -> Templates -> Styles
2 – Then click on your yootheme default style (in the Default column the star must be yellow)

3 – Then click on open with builder

4 – Click on LAYOUT

5 – Click on FOOTER

6 – You should see a Grid your customized. (If not create one with the number of columns you want in your footer)

7 – Select the Item you want to change (here we want to change the second Item)

8 – Make your changes when you finish click Save

9 – Then click Close

10 – And finally Save

If you have more questions don’t hesitate to contact me !