Adjustment is open through Clearing, and is for those applicants who are holding a conditional firm offer and exceed the qualifications they were expecting.
If you find yourself in a situation where you performed better, and would like to try for another university or course you will have a short amount of time (never later than the last day of August) to speak with other universities. Similar to Clearing, you will apply to the university directly, and only once you have made your mind up will you accept an adjustment offer which is made.
And do not rush decisions, you applied to your 5 choices after researching and visiting them. Only choose adjustment if you have researched the place you are looking to move to. Adjustment will mean you have to apply to them fresh, and you may find it could prolong accommodation and finance applications.