There seems to be several factors regarding this.
But I don't know all the factors involved, but I have had good luck with the following..
If you are going to add a group of slides to the bottom slideshow by using the right click and add method:
Before selecting the slides to be moved, click on the last slide on the bottom slideshow to highlight it.
Then select your slides and use the right click method. The slides will be placed after the highlighted slide at the end of your bottom slide show.
...
..
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When I highlight slides to put into the bottom slideshow and right click add to slideshow:
Program doesn't put them in order (e.g) number 16,17 slide goes next to 6 ... instead of after 15
I tried to CTRL C CTRL V ALSO CTRL X They don't work.
I know the keys works as I tested them in excel.
I have a brand new dell cpu. Anyone out there that can tell me what I'm doing wrong or is it the program that won't ctrl c etc. thanks

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