It looks like it's not possible to change the setting. You'd need to create a new property. When creating the property, click on Show advanced options and enable Create a Universal Analytics property
Same happened to me.
Thanks to @LukaszWiktor recommendation I was able to solve it. I would just add that once the "Create a Universal Analytics property" is checked, Google by default creates two properties, the G-XXX one and the UA-XXX; and you are redirected to the G-XXX by default too. So what you need to do is select the UA-XXX property so you can copy / paste the correct tag.