Desperate, can't update and use most apps!

Hi folks

I have researched this loads on the internet and cannot find an answer which fits my situation.
I live in the UK but whenever I do a search for apps or TRY TO UPDATE EXISTING APPS

My IPhone 4s gives me this message whenever I try to buy anything or update already installed apps

ACCOUNT NOT IN THIS STORE
YOUR ACCOUNT IS NOT VALID FOR US IN THE U.S STORE. YOU MUST SWTICH TO THE U.K STORE BEFORE PURCHASING

I have tried logging into ITunes and making sure my account is set for the UK
It is

I have been into Settings -
iTunes and app store-
but my Apple id is in light grey and I cannot click on it to change anything
I have the latest IOS on the phone
It's driving me insane! I can't get new books, apps or even update the ones ?I have!!!!

To add to this I cannot sync the phone with the computer. It says an error has occurred.
I have also read up on this and deleted any recent photos/videos



Pleaassseeee help me