I've had this issue for years and always assumed it was a windows 10 issue, but the windows 10 solution to this issue (turn off auto accent colour) has never worked for me. When doing this with many files this can be a real annoyance. If you were just about to start inserting some text somewhere in a filename, but hadn't started typing yet, then the fact that the filename has just re-highlighted itself might cause you to overwrite the entire filename instead of inserting the part you were planning. I suspect this has something to do with updating the little blue and green file icon overlays. After a second or two, when the Dropbox App has re-synced the file you previously renamed, Windows will highlight the entire filename that you are currently arrowing-around in - maybe just as you were about to start typing.Quickly start using the arrow keys or Home/End to move around in the filename but do not start typing.If the previous filename was still in the 'editing' mode then you will automatically be editing the next filename. Press the Tab key to flick down to the next file in the folder.Click on a file name twice ( not doubleclick) to begin renaming it.Open a folder containing many files that is currently synced in Dropbox.I often cycle through a lot of folders using the tab key to rename them one at a time, and this produces an issue where, as soon as the Dropbox app has synced the previous file, Windows highlights all text in the currently-being-edited filename, even if I am tapping through it. Found a reproducible annoyance in Windows 10 with Dropbox.

Better file rename review