This assumes that the USB stick is readable in the phone already, and I will not cover that part.
Yes, it might of course work with a 3rd party file manager as well. But this will cover the HTC/Android way.
Pink/purple dot indicates “tap here”.
First we assume
That the USB is properly mounted to the system, or this will never ever work.
Some USB sticks I try with gives me a “Corrupted [name of stick] USB drive”. With a “touch to fix”. Which simply formats the stick to be used with the phone.
With a good working USB stick you will simply tap “explore” to see the content of it.
The HTC way
Open the HTC file manager where you find the folder(s) you want to copy. Tap Copy, then the storage you want to copy it to and simply tap Paste. This works on One M8/M9 and so on.
If USB storage doesn’t show in the HTC file manager
This you might have to do with EACH USB stick, or new USB stick.
Eject the usb stick. Start the HTC file manager WITHOUT the usb stick connected. Connect it. Then you will see a window popping up. Just follow it. In the screenshots below Transcend is my USB stick.
If still doesn’t work in HTC file manager
Sometimes it works to simply clear data/cache for the HTC file manager app which resets the settings for it. Which means that you should try the previous step again, and it should work just fine.
Settings > Apps > File manager > Storage, where you tap “clear data”. And possibly “clear data”.
This sometimes is due to the phone being slightly messed up and need to be cleaned. And, permissions etc might be a bit messed up. After such a major update I always recommend you to do THIS.
The native Marshmallow way
This is the same method that Nexus devices with Marshmallow can use.
Open Settings > USB & Storage > [choice of storage], Internal in this case. Then you tap Explore. Find the folder you want to copy. Longpress it. Now it will show 1 selected at the top, if you want to add another folder just tap it.
- Select the 3 dot menu where you tap Copy to..
- Select target to copy folder to
- Tap Copy
If no storage (outside google drive) are being shown on the Save to step, then tap the 3 dot menu there and tap on “show internal storage”.