How to connect Arduino clones with PL-2303HX

I Want to connect M.Jduino, VISduino and pro mini with version of USB-to-serial adapter. Pictures are below I marked one of the pictures with symbols.

I found 3 different versions how to connect pro mini with usb to serial which is correct?

6 ---> u1
5 ---> u2
4 ---> u3
3 ---> u4
2 --->
1 ---> u6

6 ---> u1
5 ---> u2
4 ---> u3
3 ---> u4
2 --->
1 ---> u5

6 ---> v10
5 ---> s12
4 ---> s11
3 ---> v9
2 --->
1 ---> v1

How to connect MJduino and VISduino boards with USB-to-Serial 6 pin adapter?

And why TXD connects on RXD or RXD on TXD and not TXD on TXD?

General rules for any Atmega328-based Arduinos(1):

Arduino USB-to-UART bridge(2)
RX (0) TX
TX (1) RX
RST (or Reset) DTR through a 100nF ceramic capacitor
5V or VCC VCC or 5V
GND GND

Notes:
1. that includes any arduino that uses DIP or SMD versions of the Atmega328 or Atmega328P, and also works for Atmega8, Atmega48, Atmega88, Atmega168, in any power version of package.
2. examples of USB-to-UART bridges are: PL2303, CP2101, CP2102, CP2103, CP2104, CH340, FTDI (FT232), and so on.
3. The CTS line or any other pins present on the bridge adapter can be left disconnected.
4. Some USB bridges include both 5V and 3.3V lines. You should choose only one of them, depending on your project’s requirements. An Arduino, however, doesn’t run very well at 16Mhz and 3.3V.