You can edit the VPN connections configured in the FRITZ!Box as follows:

• VPN connections to other FRITZ!Box networks (LAN-LAN linkup) and VPN connections to company VPNs can be edited in the FRITZ!Box user interface under "Internet > Permit Access > VPN".
• VPN connections that were created with the Configure FRITZ!Box VPN Connection software and imported into the FRITZ!Box can be edited on the computer with which they were created. These VPN connections cannot be edited in the FRITZ!Box user interface.

  Note:Configure FRITZ!Box VPN Connection saves the VPN connection settings in:
  Windows 10 / 8: C:\Users\[User]\AppData\Roaming\AVM
  Windows 7: C:\Users\[User]\Appdata\Roaming\AVM

• VPN connections to iOS devices, Android devices, or computers with macOS cannot be edited.

If you want to adjust other settings, delete the VPN connection and then reconfigure the connection with the new settings.