Method #1: Keep yourself on mute always. Then, press and hold down SPACE when you want to talk. This unmutes you temporarily. See note below.
Method #2: Keyboard shortcut to mute and unmute:
In order to use the spacebar method to temporarily unmute, the option must be enabled in advance. Also note that it can’t be used if the host has prevented participants from unmuting.
To enable the spacebar option, follow these steps:
Here is the keyboard shortcut to mute everyone except the host.
Note, only the Zoom meeting host can issue this command.