Force lower case.

I want to always convert files names to lower case on the remote site. Cannot find how to set this preference n Options.

Go to Transfer page in Preferences:
https://winscp.net/eng/docs/ui_pref_transfer
And in the Defaults, set Filename modification > Lowercase:
https://winscp.net/eng/docs/ui_transfer_custom

Thanks for the reply. It did not look like Default had a submenu.