Every presentation has a theme applied to it that determines the formatting and style of the text and other objects on the slides. If you are copying between two presentations, each with a different theme, you can control the text style when you paste text from another presentation.
Select the text that you want to copy, and then click Edit > Copy.
Open another presentation, click where you want to paste, and then click Edit > Paste.
On the Paste Options button, select how you want the text to appear — for example, select Use Destination Theme to apply formatting that is consistent with the presentation that you are pasting into.
To apply the formatting of the presentation you copied the text from, click Keep Source Formatting.
The Paste Options button is available until you type or click anywhere else.