Using LOwriter 4.2.3.3 How do I save document to flash drive?
… Exactly in the same way as to any other part of the file system: > ‘File’ > ‘Save As…’ > choose drive (media) and folder, … save.
(NB: V4.2.3 may be a bit outdated. Best choice, imo, for the moment: V4.3.5 or V 4.3.6)