Excel Auto converts numbers to date format

[E_Davis1908]

We use Excel to generate our sample POs with our factory partners through our offices in Asia.  This has been an ongoing issue and we're trying to determine the cause of it.  

Normally the format is set to General and when we have a QTY listed out in multiple columns (1, 1.5, 10, 13.5, etc) I'll often get the spreadsheet back with those numbers converted into text.  It's as though someone has their Excel set to automatically convert them from Julian date format into standard date format.  

My internal partners should all be using Office 365, but there may be some factories that are not using that same version.  The issue goes back several years and in our main office we had just assumed that when the team in Asia was entering the ETA details for completion they were converting the whole spreadsheet into Date format.  When I look at other text fields, they are all changed from General --> Date formatting.  

[#2]

EDIT: One key thing I forgot to mention is that the entire workbook (4 tabs) is converted to Date format from General format. It does appear that if I set the QTY fields to Number format that they are not changing... TBD

[#3]

@E_Davis1908 

I'm not at all sure how anyone here on the boards could determine cause for you.... Indeed it's possible that somebody has their Excel set to default to date format...

What I wonder, short of determining cause, is whether it can be prevented by using Protection, applied to the workbook/worksheet in all cells except those where data entry is desired. Is such a thing possible in your environment?

[#4]

I'll use that option as a last resort.  Unfortunately my team in Asia needs the ability to change the QTY.  

[#5]

@mathetes I may have stumbled onto the source.  There were several Custom Styles that were showing on the spreadsheet.  I'm not sure of the origin, but they were labeled Normal_xxxxx (xxxx being various other names).  All were set to Date format.  The normal "Normal" had also been changed.  Opening up a fresh new spreadsheet this is in "General" format.  Could be that these were a template that's been used for the past 9 years... something my predecessor created.  

[#6]

@E_Davis1908   Part of the idea of Protection is that some cells are first "Unprotected",  set to allow entry or modification; others protected. The whole idea being that you can collect info from others but they can't make unwanted (perhaps unintentional) changes.   So it needn't be a "last resort."