Graphs are updated each time worksheets/workbooks are calculated.  Cause of
the fact that some of my workbooks, in particular my individual machine
center production files, has a lot of formulas and charts in them, it gets
to be rather lengthy, so for those set of files, I have the Calculation mode
set to Manual and Don't calculate before saving.  I use a centralized file
to do all of the data processing from start to end including calculating
each sheet one by one (that is achieved via the Shift-F9 keyboard
combination if calculating a worksheet manually).

Also, just for the record, I do not use the F9 key by itself within Excel as
it's suppose to calculate everything, but found that one to be so incorrect,
so I end up using Ctrl-Alt-F9, which forces everything in all workbooks to
be calculated, when manually done.

How can I have some files calculate automatically and others set to manual
calculation?

Well this is a bit tricky as you can't have both in the same instance of
Excel, thus one of the reasons why I setup files into groups, so as to meet
this specific requirement as well as not to exceed the amount of RAM usage
allowed within a single instance of Excel (80MB for XL97 and XL2000, 160MB
for XL2002/3).

Open Excel the first time for those files you want to have calculation take
place automatically.

Open Excel up the second time either via an icon shortcut to the program,
toolbar button or via the Start>Program Files menu.  Set the calculation
mode to Manual and uncheck the option to calculate before saving.  When you
close this instance, you may be asked if you want to save Book1.xls (or
something like this name).  Just click on No unless of course you did
something with it that you wanted to save.