Hi,
First off I want to say that the display settings to use while transferring the image to a TV using HDMI are spot on. They work very well. The problem is when using a projector......I tried using the function (Fn+f8) on my laptop which is supposed to "send" the image to the projector displaying the slideshow to the class while retaining the presenters notes etc (beside the actual slide that is being displayed to the class) on the laptops screen. Instead I had to use the option of "copy the laptop display to projector display". Don't get me wrong, it worked well but libreoffice doesn't go into "slideshow presentation mode" the way I explained here above. All it does is display the presentation slides full screen both on the laptop as well as on the projector. This defeats the whole point of the presentation when I usually have the timer running on the laptop screen during the class and I can keep track of the time I take for each slide more over it is useful for me to see the notes I prepare for each slide.
Is there anyway of using the (fn+f8) which used to work fine previously but now the "copy display" function eliminates the proper way in which the slideshow/presentation must run.
I know my problem is a bit complicated to explain but I hope someone out there gets what I'm trying to say.
Thanks in advance.

you can configure external displays in the display category of the control center. there's an advanced mode for configuring this and there you should be able to set the mode to cloning.

in LibreOffice Impress just press F5 and it will go to the slideshow mode and start the slideshow.