I would try to do a repair on you install and see if that fixes the issue.which ? in Excel itself it's the same as pressing F1.
Btw, Task manager does NOT state it as 32bit, therefore i assume it is really 64bit.
Edit: ehhh... oh this ? right there xD
View attachment 5188
Yeah 64 bit!
Windows 8.1 is build
Version 6.3.9600 Build 9600