PORT 5432 ERROR

I am receiving an error when I enter the server port number to listen
to—installed on all available versions, both 32-bit and 64-bit when
applicable, even the latest version, 15.3 x64 for Windows. I downloaded the
latest version as an example, and as I was told, I used the 5432 port as
the default port needed. I get a pop-up afterward saying, "Warning: The
specified port number is not available. Please enter a different port
number," than roadblocks at entering the default port number. I found
port 5434 available though it locks at a loading screen "loading server
Postgre version 7.4. Version 10 works on port 5434 though the server list
tree spins eternally.

Any solution or assistance would be appreciated.

Best regards,
David Beck