Currently I import my inventory via .xls and use that to create report records based on what I use during my production.

My question is how do I update the inventory without changing records made the previous day. For some reason it updates all the qty fields with the updated info and once a record is created i want to eliminate the updating. How is this done?

Day 1 Start Qty 1000 Used 200

Day 2 Start Qty is 800 but once the inventory is updated it reverts Day one start qty 800 and throws everything off.

The thing is, there is more than one "right" way to do "inventory". And I think FileMaker 10's script triggers have change the rules just a bit (for the good).

If you modify a field, and something changes somewhere else that you do not expect, then you've done something wrong structurally, or just placed a field on the layout incorrectly relationally. The trouble is, you can easily do that with relational design, when you're first starting to use it.

As I pointed out on your file, one of the fields was on the layout as a relational field when it should have been a local field. This is a common mistake people used to "flatter" applications like spreadsheets make. It may look OK, but it makes things behave strangely. You must understand why "context" is so important.