You don't need to create too many topics in order to get your answers.
You have created 3 topics but all of them are in incorrect sections.
Move one of this topic (& lock others) to the Service Discussion section and you will find a lot of answers.
Also, modify the title of the topic (Subject) so that it is not misleading. I edit it.

It is difficult to buy Bitcoin through credit card, the best way to do this is by using P2P sites like Localbitcoin or Paxful. (you need KYC)

There are some other platforms that you can find in the other topic.