After recording my screen I don't know where the original recording file is.
Beginning in Camtasia 2018 we no longer have a Documents\Camtasia Studio folder. The path is now labeled Documents\Camtasia. This is where your recordings will be. If you would like to change this back to what it was in Camtasia 9 so all your recordings remain in the same location follow the steps below:
In Camtasia Recorder click on Tools > Options > General tab and change the Output Folder to Documents\Camtasia Studio.
Beginning in Camtasia 9, by default we autosave your recording to the Documents\Camtasia Studio folder. If you would like to return to the old way of saving your recordings follow the steps below.
In Camtasia Recorder click on Tools > Options > General tab and change the File Options to ask for a file name.
Then go to the Program tab and uncheck this box.