Shouldn't Everything match search term 'ffx' to Firefox.exe?
Short answer: no
Everything will find results matching your search terms.
It doesn't have an option to match filefox with ffx.
You could match firefox.exe with:
f*f*x*
-or-
f f x
Long answer: yes
- In Everything 1.5, from the Search menu, click add to filters.
- Change the Name to: Gapped Search
- Change the Search to: regex:\b[regexreplace:$param:,(.),\1"[a-z0-9]*"]
- Click OK.
- Active this filter from the Search menu and search for: ffx
(Also, can someone tell me how Everything matches terms typed in reverse? For example, I can type "Amazing Every" to match "Everything is Amazing.txt". That's awesome!

Just curious how Everything does that?)
Spaces break your search into terms.
Everything will AND all these terms together.
The order doesn't matter.
Amazing AND Every
is the same as:
Every AND Amazing
If you want to find Every after Amazing, please try the following search:
Amazing*Every*