Excel for Dummies...namely me...LOL

JamesB62 

To supplement what Abiola1 said, if you could  upload your workbook (after rendering any personal or confidential data anonymous), we could make more specific suggestions. Abiola1 is totally correct that good practice almost always is toward having your data organized in the form of an Excel table (single rows per entity), so that you can take advantage of the many functions and capabilities (Pivot Table being one of them) to create creative and helpful output reports, summaries...

The mistake that is so easy to make is to organize your data as you want to see it, rather than as a database or table...when you do that, you encounter the kind of situation that you are seeing: how do you change something on each screen?

Another thought, if there's some compelling reason to for which you have to maintain your current organization, a way to make a change one place and have it cascade through multiple references (whether on one sheet or many) is to use a named range. (Under Insert....Name....Define....). For example, if you have a Sales Tax field (it could be anything) instead of having that field on each sheet, have a place where what are essentially constants (changing once in a while, but generally stable), enter 0.0875 into a field, and then name the range SalesTax. From then on, just refer to that name in any formulas.

Anyway, if you could upload a sample of your workbook, we can be more specific in recommendations.