Cant get posts to appear on pages with categories checked.

SIXTEEN PLUS TEMPLATE: I have watched YouTube videos, read forums, etc..and tried repeatedly to get posts to show up under the categories and pages. On home page, my posts show up, but I want to be able to click on various Menu pages (which I labeled specifically to match category names) and have all posts land on those pages which I specify. For some of my posts which are listed at bottom of my home page, I click the category and bounce over to the page, only to find that either none of the posts are there in the category, or only 1 is listed there while the rest are missing. Ultimately I want each page (menu option) to reflect a category, and clicking that page lands you to all posts on that topic. Please help and tell me what I’m doing wrong and how to fix this in order to achieve desired outcome. No tutorials that claim all you have to do is add a category and click off the category on each post, work to solve the problem. The only way you can find posts is to go to the bottom of the page and look through the list.