Just got my L14, it’s superb. It’s my first time using Linux but it’s been rewarding to learn the ropes. Installing programs and not having files on the desktop screen are a bit discombobulating, but not overly so. Anyway…
When I plug in a USB drive I can use it just fine on the L14 but when I unplug one and use it on other devices (running Windows) they must be reformatted before use. What’s going on and how can I address the issue?
Thanks.
A USB stick, like most other kinds of disk drives, can be formatted using different file systems. That choice is made when it is formatted, and then operating systems that understand that file system can use it.
It could be that in your case the USB stick is formatted using a file system that Linux understands, but that Windows does not understand. To get around the problem, you could format it on the Windows machine (note that all data on it will be lost when formatting), then after that it will most likely work on both Windows and Linux, because Linux can handle the common Windows-style file systems (called things like “fat32” and “ntfs”). I think USB sticks are often formatted using the fat32 file system and then they work fine in both Windows and Linux.
Another option is to remove Windows from the other computer and install something better for your freedom and your privacy. 
If you’re okay with sharing that info, please write something about your order date and shipping date in the thread here: Estimate your Librem 14 shipping
Be advised that if you do use fat32, you won’t be able to store files larger than 4GB.
How would I go about tranfering a file of ~20GB to my boss’s air-gapped Windows system?
Exfat is the file system I would use to meet that requirement.