Hi @fatih_basaris!
This is the expected behavior because once you send UART 1 the communication will be redirected from USB (where your terminal is connected) to the UART. You have to send SAVE from there (UART1).
You’ll have two Teraterm terminals, one connected to the USB (the one you have working now) and another connected to the USB-Serial converter, which will be fisically connected to the DWM3001CDK (header J10, pins 8 and 10 and a GND for reference). When you send the command UART 1 in the USB terminal, the OK response will appear in the UART terminal and the communication will continue there, unless you reset the board. You have to send SAVE in the UART terminal to make it default, so next reboot it will start from UART.
Kind regards!