If all you want to do is change the $ signs into £ signs, you can do this quite easily by simply changing the formatting of the cells using the drop-down menu on the Ribbon.
For a video walkthrough of this, see: Essential Skills Lesson 4-3 Format numbers using built-in number formats.
Note, however, that this will slightly change the formatting of the cells, because they're currently using a custom format. If you only want to alter the currency symbol, you can do so by changing the custom format.
They're currently using a custom format that looks like this: "$"#,##0
To switch to £ signs, all you need to do is change it to: "£"#,##0
For full instructions on understanding and changing custom formats, see the video lesson: Essential Skills Lesson 4-4 Create custom number formats.
All this will do is change the symbol from $ to £ - it won't convert the values to a different currency. If you want to convert the dollar values into GBP values, you will need to use formulas to convert them using a specific exchange rate.
For an example of this, see: Essential Skills Lesson 3-13 Understand mixed cell references.
I hope this helps, and please feel free to reply if I can be of any more assistance with this.
Jonathan is part of the professional team who answer Excel-related questions posted on the ExcelCentral.com forums.
Jonathan also tests our courses prior to publication and has worked on all of our ten world bestselling Excel books for Excel 2007, Excel 2010, Excel 2013, Excel 2016 for Windows and Excel 2016 for Apple Mac. Jonathan has also worked on over 850 video lessons for or video courses covering Excel 2007, Excel 2010 and Excel 2013.
As well as extensive Excel knowledge, Jonathan has worked in the IT world for over thirteen years as a programmer, database designer and analyst for some of the world's largest companies.
Pound sterling, the basic monetary unit of Great Britain, divided (since 1971) decimally into 100 new pence. The term is derived from the fact that, about 775, silver coins known as “sterlings” were issued in the Saxon kingdoms, 240 of them being minted from a pound of silver, the weight of which was probably about equal to the later troy pound. Hence, large payments came to be reckoned in “pounds of sterlings,” a phrase later shortened to “pounds sterling.” After the Norman Conquest the pound was divided for accounting purposes into 20 shillings and into 240 pennies, or pence. In medieval Latin documents the words libra, solidus, and denarius were used to denote the pound, shilling, and penny, which gave rise to the use of the symbols £, s., and d.
On February 15, 1971, the pound sterling was officially decimalized into 100 new pence. The symbol £ was retained for the pound sterling, and the letter p was chosen for the new penny.