179167 wordpress how to order pages

1) I need to know how to make the pages in my menu change their order to the order that I want. Currently they just go in some random order. I need to change the menu order at any time that I want. 2) I also want to know how to change the order of posts in the posts menu of wordpress. 3) I want to know know to make the first page in wordpress display only a single post of my choice, not every single post like it does normally.