Q: I changed my iPhone lately but i can't restore my last backup since it keeps saying "itunes could not restore backup because the password was incorrect" but I don't know where to put the password to make it happen... Any suggestions?

Please read this:

http://support.apple.com/kb/HT4946

... and also this which is referenced by the above:

http://support.apple.com/kb/HT1766

Pay particular attention to the "encrypted backup" references.

The password refers to one of two things:

1.  You had an encrypted backup and it needs an encryption password to unlock.  That is what I thought originally when I sent you the links above.

2.  The iPhone is locked and needs to be unlocked before proceeding.  Try unlocking the iPhone by entering its password.

Do you have a Mac?  See "Mac Only: Password Saved in Keychain" here:

http://support.apple.com/kb/TS5162

Unplug from PC.

Go to iTunes>Preferences>Advanced>Reset all dialog warnings.

Restart PC and iPhone.

Try again.

1. Select your iDevice in the iTunes.
2. Choose the Summary screen (tab) and scroll to the bottom of the screen.
3. Then un-select Encrypt iPhone backup.
4. iTunes will then prompt you to “Enter the password to unlock your iPhone backup”, enter the password you set originally.

I have the same issue & can't seem to resolve it either, even though I am following all of the above steps... This is definitely frustrating...

That fixed it for me. Thanks!

I that this is the last Apple product I will buy.  Everything is become too complicated and is starting resemble microsoft.