It seems that the parameters were being updated in another SWAT project. I was working on two different watersheds: Project1 and Project2, yesterday, I ran a scenario in Project2. This morning, I re-booted the computer, and re-ran a scenario in Project1. However, when I opened the default textinout files in the Project2 folder, the changes I had intended to make in Project1 were there. No, I wasn't accidentally working in Project2...How to avoid this, or why it happened, I don't know. But at least I know it CAN happen, and I thought I'd share that knowledge with you all...