For manual programming of my Baofengs (UV variations) with the keypad, I know that unless I hear "Saving Memory," this channel number already has data assigned to it --- and that this assigned/occupying data must be deleted before any new data will be reliably saved.
I no longer try to update any occupied channel---I simply delete the channel and program anew for that channel number.
To manually create a channel memory, using the keypad menu, I enter/ define everything I want from the keypad menu options (including tones) before saving the channel memory. Again, If I don't hear "Saving Memory," ... I don't have a reliable saved channel.
Hope this helps someone.
Best Regards!