what's your point? You don't qualify without an account so you have to get it outside and then get an account. That's a banking issue NOT an immigration.
you absolutely can change. As long as you qualify on all counts.If you do not have a bank account, you don't qualify. If you do not have enough time left on your stamp usually around 15 -21 days. There are reasons that they tell you to leave and do it out of country. But your experience, possibly lost in translation, or too much info at once.
Anonymous participant purchasing a course does not mean you have to attend as it is a leisure activities.Like a gym membership you never use.There is no attendance or accountability to it. Other visas like an education ED, REQUIRE attendance and even then are only loosely monitored.