The memory is used up – what to do?

When a smartphone's storage is almost full, its operating speed slows down and it is no longer possible to install new apps.

Use memory cards

Since you are lucky enough to have a smartphone that can use a memory card, insert one into the device. Then move large files (especially photos and videos) from the internal memory to the memory card.

Move to your PC

The second possible solution:
Move large files (especially photos and videos) from your smartphone's memory to your PC. You can do this either via an online storage service such as Google Drive, iCloud or Dropbox, or by connecting your smartphone directly to your PC via a USB cable.