I received this question today so I thought I would post it for reference. I've paraphrased it, but here is the essence of the question:
"Our accounting manager is out for the day. I just tried to post a batch , but it is asking me for a Batch Approval Password and we don't know the password. How can I change it?"
The batch approval passwords can be changed under Tools -> Setup -> Posting -> Posting. (Posting Setup Window)
You will want to make sure to select a Series and Origin before making any changes on the Posting Setup window. Do not make changes to the window without those two fields populated.
Once you have selected the appropriate Series and Origin, you should see the "Require batch approval" box checked. You can type a new password in the Approval Password box, then click OK.
After typing in a test password, I also noticed that the password is visible, so you can just check what the value is, and don't actually need to change it if you don't want to.