Josh,
Adding to Josh A's reply... Happy New Year. Making Adjustments to Inventory you have a few types:
1. First I suggest running a Physical Inventory Journal with the Posting Date set to the day you will start the count.
2. You will see NAV counted Quantities (what NAV counted and it shows on-hand).
3. You will count the inventory and enter the actual in the Qty. (Phys. Inventory) column. NAV will show the Positive or Negative effect on what NAV calculated and its Value impact on Inventory.
4. When you have finished counting, Post.
Now this is the easiest way by you can do this in Batches of Items or other filters. You can also setup Phys Invt Counting Periods, on the Item Card, which define how many times you want to count the Item. You can run Counting Periods off the Journal, which also can filter Items.
If this might be too difficult this year, you can use the Item Journal and perform Positive or Negative Adjustment entries against each counted Item. If your Item has a Value issue, say the Unit Cost needs to be revalued, then you will use the Item Revaluation Journal and reset the Unit Cost for all Items on-hand for the Item. You will set a new Unit Cost and Post.
If you need more info, reach out.
Hope this helps.
Thanks,
Steve