The spreadsheet importer tool was created as an easy way to update Item Manager settings without having to edit each item manually.
You will want to double check the formatting that the Item Manager uses for each field. Once you get an idea of the type of data that goes in each field, you can create a spreadsheet that contains the columns you want to update.
First open QuickBooks to the company file you use for your store. Export the file to a CSV file, and open it in an office suite such as Microsoft Excel or OpenOffice.org's Calc. This will give you a spreadsheet with all of your QuickBooks items in it. You can delete all of the columns except the QuickBooks Name. Keep that column as the first column in your spreadsheet.
Add additional columns for each Item Manager field you want to update. You can then mass update them using your spreadsheet software.
Be careful that if a field is supposed to have HTML code in it, that you strictly use HTML code and not regular text. The most common tech support issue is the use of special characters in HTML fields. Characters such as the ampersand (&), the degrees symbol (°), and quotes can cause your web site to display errors. Fields that REQUIRE HTML code are The HTML Long Description and Bulletpoints fields require HTML.
See the directions on the tool itself for importing the information back in.
For information on importing categories from a spreadsheet, see this page.