We are not sure why the number of questions has settled at 37 for Apostles
and the first 19 for Elders
(see profile) except to say by the leading of the Holy Spirit no further key questions are required to confirm Apostles and Elders. It is interesting to point out that Jesus' ministry started at the age of 33 and He died on the cross at the age of 37.
Apostles ("then of all the apostles" 1 Cor. 15.7) are directly commissioned by God with authority to choose elders who take care of church localities: "being built upon the foundation of the apostles and prophets, Christ Jesus himself being the chief corner stone" (Eph. 2.20).
This is not some test to determine if you are a Christian, for if you believe, you most definitely are saved (John 3.16,18; 6.47). Do not let the evil spirit make that accusation in your heart that these questions are a test of your salvation. The great accuser who accuses day and night will attempt to trip you up at every turn, misreading the purpose of these questions. However, there are certainly some things said that surely indicate one's salvation or unsalvation.