Folder overwrite on Localhost

[Media Bug]

I am currently building my site on my local pc (Windows 10). My site is currently working on localhost using XAMPP. My issue is folder overwriting. My theme package needs to be updated to the current site. The folders in the updated theme is the same as the folders in the htdocs folder on xampp. When I try and copy and paste the folder (app) to overwrite the existing folder (app) it makes a copy of that folder, making it a subfolder with the same name (app). I cannot figure a way to just overwrite the existing folders. There are many folders and subfolders that need to be replaced. Is there not an option, software, etc that will let me replace these folders. For my sites hosted on my servers I can use Cuteftp and/or Filezilla to upload the folders and they overwrite as needed. Surely there has to be a simple way. In the past for a small folder I just copy and paste the files within each folder and overwrite them that way. However this is a bit many to do. Thanks in advance for any assistance.

[sivashchenko]

I'd try to drag-n-drop the "app" folder with updates to the folder containing existing "app" folder (NOT to/on "app" folder) and confirm the rewrite in the popup.

However, I'd expect the new theme only to add files to 

<magento root>/app/design/frontend/<ThemeVendorName>/<ThemeName>

Files in any other directories should not be changed/added by a theme (if it's Magento 2 )

[theMageComp]

Hello @Media Bug 

If it is only theme folders inside, it won't overwrite any of the core Magento folders.

Please make sure you are not copying a quickstart package of theme because that can overwrite your core Magento folders.

If your current store is not in production mode (sales not started yet) then you should try quick start to quickly install the theme with Magento setup.