I've set my lockscreen to a slideshow, and it somehow finally works now.

However, how do I change the lockscreen interval? It's too fast (like 5s) and I want it to only change every hour.
How do I prevent the slideshow from showing a collage of wallpapers? (I only want to show 1 wallpaper at a time).

If there's an app, there must be the option to use pictures from my own folder, as the laptop will be on a metered connection.

Laptop stats:
HP Pavillion dm1-4002AU
Windows 10 Home 64bit (upgraded from Win7 and then reset to a fresh state)
AMD Radeon HD 6230 Graphics