The 5 digit PIN is a number you selected at one time when you were in the File section of the program. It will be used each tax year if you transfer the prior year tax return tax data to the current tax year. It is Not a security feature to prevent someone one else from using your personal information to file a tax return.
For that type of protection you would need an Identity Protection PIN from the IRS
Go to this IRS website for the IP PIN - https://www.irs.gov/identity-theft-fraud-scams/get-an-identity-protection-pin
