The instructions I gave were for the mobile edition. I see now you're using the desktop edition. When your people are with customers, which edition are they on? I was imagining them "in the field" and using a mobile device.
On this screen, the Play button is labeled as Run, because you're in developer mode here. If you have the entry itself (in user mode) before you, the Play button is not labeled, but it appears as a standard Play button (like in YouTube) without a label.
As for the inventory number, Memento doesn't put commas into integers, so you must be using a Text field or importing or something. I assume you're not needing to calculate with the inventory numbers, so a Text field should work fine, but with a Text field, there is no option to autoincrement the number, and if there are commas in the numbers, your people must be adding them themselves!
Option 1 would be for them to save the keystroke and not type it in. Option 2 would be for you to use an autoincrement Integer field instead of a Text field, and commas would not be able to be entered. Option 3 would be for a script to remove any commas from a Text field. So, assuming you keep it as a Text field, we need in the script to autoincrement the number even though it is a string rather than an Integer, and we need to remove commas.
It sounds to me like you need to learn some JavaScript. Do 2 things...
1. On an Android device, go to the Google Play store and install Grasshopper, the app for learning JavaScript. Then take the 1st 2 courses, called Fundamentals 1 and Fundamentals 2.
2. Search the forum for messages whose subject line starts with "Bm". These are my "Bill's mementos" -- newsletters that for most of not all of this year contain articles that are chapters of Beginning Memento JavaScript for Nonprogrammers. They are sent more or less monthly, though I missed both March and April. The May issue will be coming out very soon with chapter 3 of the course, which starts to move you into objects. It goes very slowly, but that seems to be what beginners need, so it'll take all year to finally get to all the tricks you might want, but it'll be worth it if you frequently have needs for customizing your use of Memento.
I'll update the Teresa library with a Text field for the Inventory number and a new script to do the comma stripping and autoincrementing. When you see the Text field and a comma-stripping script appear, I'll be done, and see what you think. I'm doing everything on Android devices, as that's what I have and use. Something could be slightly, annoyingly different on the desktop edition. Give me some hours. I have to eat and run errands today, but I'll get to it.