Using Simple (Straight-Through) vs. Cross Cables in Home Networks: Router, ADSL Modem & Switch

Hello
I set up a network at home and read in various topics that once a cross cable is used, sometimes a simple one (twisted pair of course) when and where is it used?
At the moment I have a computer connected to the computer and I do not know what cable because in the store I said that 2 computers directly, and I am going to use a router with an adsl modem and a switch and connect these computers (and then 2 more) and I got ready to connect them with what cable . On one of the cables coming out of this switch, I am going to use a splitter of some switch or hub because I do not want to let go of 2 cables next to each other because 2 more computers are far from the first (next to the first there is a switch) here is the diagram

If computers are to be connected directly, crossover cables are used. (but there are no directly connected computers in your drawing).
Simple cables are used for other connections (although some routers can recognize and support a crossover cable)

Generally
- simple - devices of various types, e.g. computer-switch,
- crossover - devices of the same type - e.g. computer-computer, switch-switch

Modern switches recognize by themselves what device is connected (auto MDI-MDIX), so the crossover cable is only needed for computer-to-computer connection.

that is, in my diagram, all cables should be straight,
what about this switch switch connection? there should be a crossover cable ??

If you have a switch with auto MDI-MDIX function, it doesn't matter what the cable will be.

If they are switches without this function, the wire between them must be crossed.

Last time, I thought I had made it clear enough.

I just like to be sure

thanks to everyone for your help