Unfortunately, default values in Airtable aren’t really what you would expect. They only work under a few unique situations. The only bulletproof way to get a true default value in Airtable (that works under all circumstances) is to create an automation that will set the values that you want.
2024 update: Default values in Airtable now seem to work under all circumstances... even if the record is created through a form or through the API!
Also, for even more control over default values, you may want to explore Fillout’s advanced forms for Airtable.
Fillout offers hundreds of features that Airtable’s native forms don’t offer, including the ability to set default values conditionally, the ability to update existing Airtable records from a form, display Airtable lookup fields & Airtable rollup fields & Airtable attachments & formulas on forms, dynamically & conditionally filter linked record fields by any values that you would like, perform math or other live calculations on your forms, accept payments on forms, create multi-page forms with conditional paths, create new linked records on a form, and so much more.
Hope this helps! If you’d like to hire an expert Airtable consultant to help you with anything Airtable-related, please feel free to contact me through my website: Airtable consultant — ScottWorld
If this is a form view (and not an interface form) you could try using a hidden prefill and send people the url with the hidden prefill. You can use the Prefilled Forms extension to build a formula for the url, or just build the prefill yourself since it doesn't involve existing field values. People will still be able to remove the prefill from the url, but it might be close enough for your use case.
Prefilling and hiding is also possible in the interface form.
The usage is exactly the same.
Prefilling a form via encoded URL | Airtable Support
I actually did something simple.
Created a formula with nested IF statements to input the correct value, based on another field's entry. I also removed the input box on the form.
Thanks all!