Steam is kind of strange about letting you move things around on your own computer, but it can be done. Windows makes that situation worse with what it does to mods applied in the Program Files directory. It's easiest to change the "Library" before you install the game through Steam, but it can be done afterwards by creating a new Library folder. That part is easiest to do if you have a 2nd hard drive in your computer. Here's a screenshot from my computer:
It shows the order to click things to get the dialog. That is in the Steam app on your computer, not online. The posting is post #4850 from the FotRSU thread (page 324) from back in July:
http://www.subsim.com/radioroom/show...81#post2508481
You can see that Steam still resides in C:\Program Files, but my Steam games are in the F:\Games folder.
When you install SH4 in Program Files on a Windows computer (other than XP), the OS will "protect" the "data integrity" of the folder, unless the edits come through a "duly authorized Windows interface"... ahem...
JSGME is NOT recognized by the modern Windows (it's not "registered") as being allowed to change files, so the CFG and other files of that sort are "restored" to their former state (un-modded, in other words) by Windows. All this to protect you from yourself. What you end up with is a mixed-up mess of a combination of Stock, Mod and Windows, that sometimes won't allow the Stock game to work, even after you de-activate the mod.
Here is the "official" Steam 'blog' on moving after-the-fact:
Method #1 - Moving a Steam Installation and Games
and the "not-so-old" way:
Method #2 - How To Painlessly Move Your Steam Library...
THEBERBSTER also has the 2nd method on his tutorial page
SH4 <> TUTORIALS <> HOW TO DO IT... thread. My Steam install on an older Win8 laptop does NOT like the 2nd method, and trashed everything Steam. I had to re-install the whole shmear, and that took most of a day on the lappy's wireless. I have no idea how Windows 10 would treat you in this. If you've only got a C: drive, Steam probably won't let you add a 2nd Library folder, and you'll have to "move" things like #1 above...
