Excel 2007 : Changing all dates at once on a spreadsheet

[dotx]

I'm a freelancer and I use a spreadsheet to keep track of my daily earning. I started using it in 2010, so I now need to change the dates to 2011 (this will make a lot more sense once you look at the picture). I'm sure there's a way for me to change all the dates at once to 2011, but I can't find it. I've tried different things but everything seems to mess up the dates. Help?

[royUK]

The image doesn't indicate how the dates are generated, a workbook would be better.

Normally the first date would be entered in say A1, then in the next row(A2) enter =A1+1. Format as date & copy down

[DonkeyOte]

You may also find running an Edit -> Replace on your dates Replacing 2010 with 2011 would also work but as Roy states a formula approach would be better.

[dotx]

Thanks for answering. I couldn't make either option work, so I ended up changing the dates manually, one by one. I'd like to figure out how to do it the right way, though, since I have other spreadsheets that also need to be adjusted. I didn't create this one (I downloaded from a website), so I don't know what formula they used (as you can probably guess, I'm also not really familiar with Excel, so I'm a little lost).

[royUK]

Is the workbook protected? Post the link or attach it here