Problem with Serial Monitor on Windows10

Uploaded sketch, doublechecked baudrates, but still Serial Monitor does not show me correct symbols. Is it problem with Windows10? Who faced with such?

Did some troubleshooting, looks like this is not Windows10 problems, but board and FTDI bridge. When I switch everything to 5V Serial Monitor starts reflecting correct symbols, but when I switch to 3.3V (both bord and FTDI bridge) not.

WHY? I need board to work in 3.3v mode (powered by li-po battery)