Another way you can try to change it is on the registry:
Press WinKey + R, type Regedit and press enter. On the Registry Editor, go to the following key: (you can copy and paste the address on the address bar)
HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\PassportForWork\PINComplexity
On the right side of the window, find the value MinimumPINLength , if it is not present, right click > New > DWORD (32-bit) Value, and name it MinimumPINLength double click the value and on value data insert the desired value. Restart the computer to apply the changes