Cannot change the configuration status from modified to appiled in the device tab of openwisp server

[Kolla Honey]

Hello, I m new to openwisp, I have installed openwisp controller in my ubuntu system. I have done auto registration my access point to the openwisp server. I m also able to make remote configuration using send custom command and able to check those changes in my access point. But I m unable to change the configuration status in the devices tab from modified to applied. What I need to do now?