When you edit spreadsheets using Excel, occasionally Excel will alter the contents of your spreadsheet. To prevent this from happening it will be necessary to set the format for certain fields.

To set the format of a field in Excel, highlight the field or fields, right click (or apple-click on mac), and select 'Format Cells'.

For UPC fields, select 'Custom' and enter 12 zeros (or 14 if you are using EANs).

For multi-character ID's, such as YouTube videos or channels, set the format as 'Text'.

You may also have other data in the sheet that needs formatting, such as any artist or track names that start with mathematical symbols - set the format for these as 'Text'.

If done correctly, you should be able to save your spreadsheet and re-open it and see the fields are saved correctly.