I would NOT change my ethnicity because if the client wants an X and you get the shop and the video shows a Y performing the shop, the shop could be invalidated. Plus if you indicate you are an X you will not be eligible for any shops that need a Y. Play it straight.
@Rosseau has it absolutely correct, many companies are hesitant to have a newbie shopper take on their first shop unless they know the shop to be non-critical in terms of demands or timings. Some are very clear that you 'must have an 8 or better shop rating' and the platform automatically rates new shoppers at a 5. Take a low paying shop or two that lingers on their board, do a bang up job of it and that will get your rating up where they can see you as a credible shopper.
One other thought, are you and your boyfriend at the same address, using the same phone number for contact? With some companies this can be a flag that a shopper is attempting to beat rotations by registering multiple times.