Is it possible to reduce the submission ID number from 16 to 6 for a Scholarship application?

I am not sure if I have understood your question correctly. Do you want to generate a 6 digit submission ID?

Unfortunately it is currently not possible to customize submission id. I would suggest you to please add "Unique ID" widget in form which will generate unique id for every submissions you receive. Please note that it is also possible to customize unique id as well. You may like to take a look at the following guide which should help you: https://www.jotform.com/help/79-How-to-Add-Custom-Unique-IDs-to-your-Form-Submissions 

Hope this helps.

Do get back to us if you have any questions.

Yes, I would like a 6 digit submission ID number to be generated to the customer after completing the application. The longer number threads were cumbersome and when included in the Subject line of an email which was needed to identify a customer it wasn’t convenient at all. Looking for a way to set up the submission ID number to be 6 digits instead of anything over.
Also, there can’t be an error of two people receiving the same submission ID number.
Thanks,
Sent from my iPad
...

Yes, I would like a 6 digit submission ID number to be generated to the customer after completing the application. The longer number threads were cumbersome and when included in the Subject line of an email which was needed to identify a customer it wasn’t convenient at all. Looking for a way to set up the submission ID number to be 6 digits instead of anything over.
Also, there can’t be an error of two people receiving the same submission ID number.
Thanks,
Sent from my iPad
...

Unfortunately, you cannot change the submission ID, it is generated by our system by a special algorithm.

But you can use the Unique ID widget: https://widgets.jotform.com/widget/autoincrement since you can customize it and it will be unique.

Hope it helps.

Thank you!