Encrypted volume locked; cannot access encryption key file

[qthim]

Hi,

Volume 1: Encrypted with Save Encryption key "enabled"
Volume 2: Encrypted with Save Encryption key "disabled"

With each reboot, Volume 1 would automatically unlock & mount, Volume 2 required a password to unlock and mount. All good.

Recently, I locked Volume 1 via "Lock this volume"
I was not asked for any password/key and it proceeded with locking the Volume.

Now, I cannot unlock it. It asks for "Input Encryption Password" or "Upload Encryption Key File".
I do not have the file as it was stored on the NAS and I am not sure I remember my password from last year (providing that original password is still valid).

I have tried rebooting in hope it will automatically unlock as before (it doesn't) and have tried the default password "admin" (as I read somewhere that if you don't set a password for encryption, then "admin" is the default).

So basically, main questions are:
Q1. Is the original password still valid? (from when volume was created, given that I have not changed it since?)
or has my "locking" of this volume somehow changed/reset the password?
Q2. Isn't the Encryption File still saved/stored/sitting on the NAS? (given it's been there the whole time)
Why doesn't it automatically unlock & mount? Can I browse/find the Encryption File somehow and use it to unlock the volume?

System: Windows 7, Firefox, TS-469L, version 4.0.5 (2013/11/29)

[qthim]

UPDATE:
After remembering my password, I tested various combinations and conclude that:
Every time you carry an action which has, as an option, the ability to "Save the Encryption Key", you are in effect setting/clearing this setting.
So if you choose not to select it, you are in fact clearing the setting, so the Encryption Key saved on the NAS will no longer work!

Regards