After much help from you all in this Group, I finally got my TS590-SG running very well however I noticed strange behaviors on the subject. Following the Kenwood recommended settings I ticked the "Fake it" option in the Radio tab. No issue there until recently when I chose to park my Red post above 2200 (trying to avoid the crowd below), the CAT changed the VFO by +500 hZ on transmit. Exactly what should happen as very well described in the "FT8 hinson guide" and returned to 10,136 on receive. VFO A in use did not go to B during transmit (as I read some other places it would do) The change in frequency was going from 10.136.0 to 10.136.5.on the radio display, 10.136.000 to 10.136.500 on the computer screen. Then I noticed several changes on the computer screen. 

# 1.  The green post mark remained under the red one despite the fact the fellow who was answering my CQ was way up the band (2400)

# 2.  The Tx and Rx markers (just below the Decode Tab) became grey out, both indicating my frequency (2250). They were like disabled. Kind of annoying as I like to see if the frequency of my correspondent is more or less clear. I was only able to move them back (after the 73 completion TX)  up or down using  new values by Ctrl + click or Shift + click to new spots.  Reading more details in the "FT8  tips" I see what is happening, (shift of the generated audio down or up) well explained and the remark at the bottom of the page  "don't panic....it's all under control".   

So my questions are:  Is this behavior of the posts normal ? Should I keep this "Fake It" permanently even if I choose to transmit below 2200  and above 1200 ?  What about the third option "Rig" ?

I tried both "Fake It" and "None" within that range and don't seem to have any exchange problems. The green post moves to where the station responds.

Last comment: I love that 590 G....what a difference with my old boat anchor !

Jacques  W2/F2YS