I do not know what you want to do.
You have only wrote us that you are looking for "Optimize connection buffer size" option. You have found it now.
If you want to turn it off, then turn it off.

ok and remove this ? (turn off?) https://prnt.sc/gXLRtgS7oo0O

Go to the Login dialog (Ctrl+N), select your stored site, click Edit, and then Advanced. Go to the Connection page.

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What do you mean? I've responded you at the same time, I've responded everyone else.
The option is exactly, where I wrote it is in my previous post above:

You find the screen by clicking Advanced button on the Login dialog and going to the Connection page.

What you have posted is a screenshot of the "Preferences" dialog.

Hahaha you are so fast when someone gave you 1 star. Here you are - please give me EXACTLY
where is this option https://prnt.sc/PLA0VsbHI1Cq

So you gave us 1 star review, falsely claiming that our documentation screenshots are obsolete:
https://sourceforge.net/projects/winscp/reviews/
And yet you ask for help.
The answer is still the same: the screenshot in the documentation is up to date:
https://winscp.net/eng/docs/ui_login_connection
And nothing has changed about that screen for over 10 years!
You find the screen by clicking Advanced button on the Login dialog and going to the Connection page.

Hello, I need find option "Optimize connection buffer size".
On the help page there is very very old image and there is no connected with the last version of WinSCP.
I need EXACTLY step by step where is this option.
Thanks!