It sounds like you have encountered an issue with the data type of the cell linked to your spin button. By default, Excel uses the "General" format for cells, which can cause unexpected results when working with numbers.

To fix this issue, you can change the format of the cell linked to your spin button to a number format that supports negative integers. Here's how:

1. Right-click on the cell linked to your spin button and select "Format Cells" from the context menu.
2. In the "Format Cells" dialog box, select the "Number" tab.
3. In the "Category" list, select "Number" or "Currency" (depending on your preference).
4. In the "Negative numbers" section, select the option that displays negative numbers as "-1234" or "(1234)".
5. Click "OK" to apply the new format to the cell.

Now, when you use the spin button to decrease the value, it should display negative integers within the range you specified (-10 to 10).