Ok, caveat: not sure if it really changed anything, so the following could all just be wishful thinking! ;-)
First of all, I found the Opensubtitle Agent on Flex to be one weak spot, so I disabled that.
Once I found an SRT file that matches and seems well translated, I open it in Notepad > Format > Font, and change font to at least 16, and use Consolas font.
Save, mux it with mkvmerge GUI (part of mkvtoolnix, found at bunkus.org)
At any rate, it's still not as big or as clear as watching via my DVR or other devices connected to my TV, so I'm using Plex less and less unfortunately....
Pretty sure that the formatting changes you are applying are only for Notepad - that is, how it is displayed in Notepad, nothing else. SRT files are just plain text documents and don't store information like a Word document does on how they are to be displayed. I think that no matter what font and size you select in Notepad, the subtitles will appear the same way in Plex until they get all of bugs/glitches worked out.
That's what I thought too, but they WERE readable, whereas when the Plex Agent grabs the subtitles they are wayyyy too small. So formatting is going on somewhere, somehow?
