The use of Zoom has skyrocketed in recent days because of the closure of businesses in response to the COVID-19 pandemic. Take heed of a FBI warning about 'zoom bombing'. The FBI's Boston office issued a bulletin that there have been multiple instances of Zoom hijacking. An uninvited person will enter the video conference for the purpose of harassing the invited host and his or her guests.
The Bureau recommends that a Zoom host use the application's waiting room feature, which allows the host to admit guests one by one. The video camera of each participant can be reviewed before it goes 'live' in the main meeting room. Enable this in the online settings under Personal . . . Settings . . . Meeting tab.
Turn on the Waiting room setting.
Also click on your photo icon in the top right and check for updates in the drop down menu. Zoom updated its software in January 2020 to prevent random scanning for meetings, and required passwords by default.