You only need to change the address on your UK driving licence, if you are a resident in the UK. If you live abroad, but you still have your UK driving licence, then you don't need to notify DVLA of your new address (they can't handle foreign addresses anyway).
If you live by your friends, but you are not considered as a resident, then you still don't need to notify DVLA about your new address. Of course having a proof of address is kinda useful in the UK, and one of the ways is your driving licence, so while it's not mandatory, you might still want to modify your address.
To change your address one way is to fill out the "New Address" part on your counterpart driving licence, and then send you licence to DVLA. You'll get your new licence via post in 1-2 weeks.
Alternatively you can also apply to change your address online. However they will ask you for your residence in the last 3 years, and if you came from an EU country, and were not living in the UK for at least half a year they will not consider you as a UK resident, and will not allow you to continue the process. If you finish this process they will send you a letter where you have to send your old licence back to them. You'll get your new licence in 1-2 weeks.
I assume that in both cases they'll verify your address by the fact that you'll have access to the mail at that address, as the licence will be sent there.