Every address you buy answers on two ports. 12345 speaks HTTP. 4444 speaks SOCKS5. The username and password are the same on both.
Use 12345 when the program asks for an HTTP or HTTPS proxy. Browsers and most automation tools fall into this case.
Use 4444 when the program asks for SOCKS5. That is the case for programs that do not speak HTTP and need the proxy to carry the whole connection.
The line the panel gives you already comes with the right port for the protocol you pick when copying. Switching from one to the other changes neither the address nor the password.