I recently realised that I wanted to swap around my firm and insurance choices for university, I had accepted my offers over a week ago, and the internet articles I read made this sound like an incredibly finnicky and worrisome process. In reality, it was far more simple than I had imagined. Note, I did this mid June, from what I understand if you choose to make this swap much later it gets more difficult. If you made your decision less than a week ago you can just change it on UCAS's track directly, this is for if you have passed that deadline.
Step 1: Contact your insurance choice
The first thing you need to do is contact your current insurance choice, and make clear of the situation. You can do this via phone or by email, I phoned my choice but they requested that I email them so they had written proof of my request.
You will need your UCAS ID, and if the university itself has given you your own student ID, you may as well have that written down too, although both universities I contacted were happy enough with just my UCAS ID. It is also advisable that you get down the name of the person you are speaking to on the phone, as this will be useful if problems arise, it is also good to note what time the call took place. Of course if you contact via email, neither of these are necessary.
So, what happened? I emailed my request to the university, and within a very short time span I received a reply, and the university told me that they approved of the change to UCAS. You can do step 2 before you get a reply from the insurance choice.
Step 2: Contact your firm choice
Next you will want to contact your firm choice of university. This was also incredibly easy, as with the last one you will want your UCAS ID, any other student IDs, and it goes essentially the same way.
I had been warned that sometimes universities will try to beg of you to stay, so I had prepared an awkward conversation with my firm choice having to explain the reasons for my swap, but this never actually occurred. Maybe my firm choice was just a really great place (spoiler, it is). So it may be necessary, but you may as well tell the truth, a university will not want an unhappy student so they will likely be more than happy to change it for you.
After this, the university will also contact UCAS and approve of the swap of your choices, for me this actually happened almost instantaneously to my surprise, and then you can proceed with the next step.
Step 3: Contact UCAS
When researching online this step didn't actually seem to exist, and I was awfully confused when both of my choices told me I need to contact UCAS, so I am making it clear here, this step is *necessary*. You do have to contact UCAS, but you contact them last, after both of your universities have contacted them.
You'll have to confirm with UCAS that you want this change to happen, they will tell you that both universities have approved of this change and they can therefore do it for you. After that the person you contacted will make the manual switch for you, just refresh track and you should see the change! (and obviously receive the track updated email)