Select the cells with the dates
Right-click and choose Format Cells
Go to the Number tab
Select Date or Custom
Choose the desired date format
Click OK
Use the Text to Columns tool if dates are stored as text
Enter a formula like =TEXT(A1,”mm/dd/yyyy”) to convert the format
Copy the formula results and paste as values if needed
Use Find and Replace to swap separators if necessary
Check that the cells are recognized as valid dates before formatting