Sounds like whomever sent the file to you marked it as Read Only,
indicating that they wanted you to be able to read it - but not change
it in any way.

If you think that they did not mean for it to be Read Only, contact
the sender and ask them to send it again with full rights.

--
J-Mac

I don't think it would be a file marked as readonly--that would stop you from
saving it as the same name--not making changes.

Is the worksheet protected?

If it isn't...

The only time I've seen this is when the original workbook was created in a
different program--crystal reports or Lotus 123.

There were areas that I couldn't format.  But if I included a few "sacrificial"
cells in my selection, made my changes to all of them, the formatting would
take.

Then I went back and fixed the sacrificial cells to the way they were supposed
to be.  (Try a cell way out of the way of where the data really is.)

===
You may want to try copying the cells, then paste special formulas and paste
special formats into a new worksheet to see if you can format the cells then.