Password works on MacBookPro but not on iPad or iPhone

Hi,

I have a MacBookPro 3.1 (purchased in 2007). A few years ago, I bought an iPhone and I bought an iPad2 twelve months ago. At first, my Apple ID password worked across all devices. Now it only works on the MacBookPro. I have reset it many times from each device, however the problem never resolves. The only thing that I can think of which has changed is that I upgraded to IOS 6.0 on the iPad and iPhone.

Now if I try to download anything from iTunes or download an app on either the iPad or the iPhone, the password is deemed 'incorrect'. However, I can use my password to download from iTunes on my MacBookPro. I also (today) used that password to upgrade to IOS 6.1 on the iPad and iPhone.

Is this a problem with synching the devices? Or is it another problem altogether? I would appreciate advice on how to ensure that the same password works on all three devices.

Many thanks,

F.