MAMP 5.7, macOS 10.13.6, Apache - How to make certain that I am NOT serving to the world (I want to be ONLY be secure localhost)

I noticed an unusual event that alarmed me (I’ll get to that later) about the security of the MAMP localhost environment that I have set up to develop a WordPress site locally, then deploy to my webhosting service. To be clear, I do not want to serve as a webhost, just develop a WordPress site locally, and be secure in the process.

THE PROBLEM / EVENT : After completing local work on a site and uploading the files to my webhosting service to serve the WordPress publicly, I was going through the remote files to correct stray link pathways in order to display images correctly. (Eg: img src="localhost:8888/Example-folder/image-file" should be "img src="remote-host-name/Example-folder/image-file"). Most were displaying one was not.

THE QUESTION: How to check that there is no switch or port that is open to the world, (MAMP 5.7, macOS 10.13.6) and if so, how to change the setting without losing localhost functionality so that I can continue to develop WordPress? Hope I’m being clear here. I want to check both MAMP Apache server and the Apache server that is native in Mac OS X to make sure that they are secure, not open or responding to the world.

I have no idea which version Apache I’m running or how to find it, however I am running MAMP 5.7, and macOS 10.13.6.

I know that it’s a pretty big ask, but being a novice at server administration I would need step by step, iei.e.: 1.open this item at location. – 2.do this – 3.etc.etc – 4.etc. etc.