How do you add multiple design templates for Powerpoint?

I'm not sure how to use the Slide Master, but all I basically need to copy and paste different slides from different files, which ALL have different design templates. But when all combined into one presentation, the slides all change to one design template. So how do I have slides with different design templates in one presentation|||In the power point the design of the slides can be customised so that the different slides will have different design.Just select the slide that is listed in the left panel and then right click on the specific design template that is listed on the right panel.Right click on the slide from the pop-up select "apply to selected slide" .In this way one can have multiple design slides to one presentation.|||Let's assume you didn't tamper with Slide Master (why would you want a powerpoint presentation with different templates anyway?). First off, when you choose a design template, all slides will match with that template. But you can customize each slide in your presentation by going to Format...Background...*click down arrow*...and then choose either a solid color (from More Colors), or you can go to fill effects where you can play around with colors that you want. Then you can apply it to that one slide or all slides!