When you have fully accomplished the logbook with all checks and completed information, you may click the SIGN OFF button at the bottom of the logbook page to close and lock the logbook for that day.

However, if you have missed some parts of your logbook that are required to be completed, a reminder box will pop-up, like below.

You need to go back to your logbook and complete these missed fields.
Once cleared and everything is good, you can sign off by signing your name in the Signature box, and click on the CONFIRM SIGN OFF button. This button will only be activated once the Signature pad has been used.

If you are signing off an INCOMPLETE ENTRY on behalf of the previous Master, you can mention that in the Handover Notes section before clicking the CONFIRM SIGN OFF button.
If you made a mistake on your signature, you can try again by clicking CLEAR PAD.
*Note: Once a logbook has been signed off, it will be locked and no further information can be added or edited.