If you're unable to find a Matter during the override process, this means that the Matter is Closed.
Only users with Administrator permissions will have access to the 'Matter Numbering' tab.
For more information on Matters that aren’t visible on the Matter Tab, please click here
Matter Number Override will modify the 5 digit automated Matter Number that was assigned upon Matter creation. For example, if Clio assigned the Matter Number 00001-Smith it is possible to use the Matter Number Override to change '00001' to '12345'.
Go to Settings
Select Firm Preferences
Select Matter Numbering
Click Open in the "Matter Number Override" section at the bottom of the page
Enter the Matter Number you want to change in the "Matter" field
Enter the new Matter Number you want to change it to in the "New Matter Number" field