Sadly, buying USB sticks has become very difficult because 'criminals' have found a way of faking the capacity of the stick. Fundamentally they take an 8gb stick and somehow make it display itself as much bigger. You won't notice until you reach the original capacity and then the stick will start playing up (namely, not storing any more data). Your 32gb stick sounds like one of these.
This happened to me a few days ago for a Stick I bought from 7dayshop, and Amazon Prime after even reselling them.
Two ways to test the stick:
a) Copy data to it till it is full. If it is painfully slow (less than 10mb/s), or fails well before the advertised capacity, you have a fake.
b) Use some Freeware software called
h2testw which will do it for you (though I found the output from it confusing, so used method a afterwards).
Alternatively, pay the extra for a big brand manufacturer (kingston for one) who print the capacity on the outside of the stick, so should be fine.
Regards to your 64gb stick, USB 3 sticks have to be put it in the back of the box
