I'm sure you are used to logging in to Amazon to buy bits and pieces, or to catching up with social media on Facebook. You may also be used to downloading from apps stores. You have accounts with these so you can buy/use their services. Each of these uses the same technology as 'clouds' and you could see each of these as being a 'cloud'. There are lots of clouds, in the same way there are lots of high street stores and they all offer different services. Microsoft and Apple both run cloud services for their users, Microsoft's cloud is OneDrive, Apple's is called iCloud and the service they offer is to store your data, documents and photos for you . (There are lots of data storage clouds.)
The advantage to storing your data in a cloud is that it is not all in one place (only your computer), so if your computer is lost or damaged, you can still access your data. Also, if you don't have access to your computer, you still can get access to your data using, perhaps a smartphone. It also means that you can buy computers that need less storage space (but you do need increasing amounts of processing power).
Cloud providers would not get much business if the word got out that they lost or allowed unauthorised access to your data. Using a good, strong password helps.
However, both Microsoft and Apple now make it easier to store your data in their clouds than on their devices. Marydoll posts how to save individual documents to your Windows 10 PC. You can also set your PC up to always use your PC's hard drive for storage.
I'm not really sure that computers are getting more complicated but believe that programmers and designers should spend time working with some Gransnetters!