To change date format to MM/DD/YYYY in Excel, select the cells containing dates, then right-click and choose "Format Cells." In the Format Cells dialog, go to the "Number" tab, select "Date" from the Category list on the left, and look through the available date formats to find MM/DD/YYYY (or a similar format matching your region). Click that format and select OK.
Alternatively, you can use the keyboard shortcut Ctrl+1 to open Format Cells directly. If MM/DD/YYYY isn't listed in the preset formats, you can create a custom format by selecting "Date" category, then clicking on the Format Code field at the bottom and typing the custom code: mm/dd/yyyy (lowercase). This ensures Excel interprets the format exactly as you want.
Note that changing the format only changes how dates appear—it doesn't change the underlying data. If dates are stored as text rather than actual date values, they may not format correctly. You can verify this by checking if the dates are left-aligned (text) or right-aligned (numbers/dates) in their cells. If they're text, you may need to convert them first using the Data > Text to Columns feature or a formula like DATEVALUE().
This approach works the same in Excel for Windows and Mac, though the menu locations may vary slightly between versions.