Were you found ineligible for Medicaid based on your immigration status since 2018?
--- YES
Have you had a change in your immigration status since you were found not eligible for Medicaid?"
--- I would answer "No". If you say "yes" it implies that something changed that makes you now possibly eligible for medicaid.
The previous question made it clear that you are ineligible for medicaid based on immigration status since (I interpret this as "after", in this case) 2018.
This does not apply to those who are not seniors, but yes, it is similar