Hello
Unfortunately QuickBooks overwrites the entire Item record when it matches the same Item name on the IIF file. I wish we could do something about that.
What you can do to avoid this is to disable exporting Items in TimeMaster (uncheck Setup->Quickbooks->Export Items).
Some versions of QuickBooks will automatically create a new Item for you when it can't find an Item referenced by a time record, but some other versions require you to have that Item already present. Please, see how your version behaves.
If it add them automatically, then you only need to edit the rate for the Item and add whatever description you want.
If it doesn't, you will need to add it manually.
Thanks,
Ernesto.