Applying for the rest of my tuition fee

Hello, I am wanting to increase my tuition fee loan to the full amount of my course fee (was previously intending to pay part fee loan 3/4 and part debit card 1/4), due to a change in circumstance, and was wondering whether on the 'tuition fee loan request form' I write the additional amount I require, whether I write the total amount (previous amount I asked for + the rest of the cost I now require) or whether I just tick the 'pay full tuition fees from this university' box? Thank you for your time, help much appreciated!