Back out of MyCareer, go to features and then select Shoes (or whatever it's called), select the brand you want and then select edit. Then you can save it and you can purchase them in the MyCareer store.
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Anyway, played some online stuff for the first time in a while and the connections seem a lot better. They're still slightly annoying but it's playable. 5v5 on the park is just awful so I tried 3v3 for the first time and it's a lot of fun.
Also, is there any way to flip the 2K camera in Park mode? When you're playing on a certain side and on offence you have to look at the backboard and I hate it. Wish it would automatically flip when it switches from offence to defence.