Apostle

The same holds true for the call of Apostle. The original call was to testify of the resurrection of Christ:

21 Wherefore of these men which have companied with us all the time that the Lord Jesus went in and out among us,
22 Beginning from the baptism of John, unto that same day that he was taken up from us, must one be ordained to be a witness with us of his resurrection. (Acts 1:21-22)

1 Paul, a servant of Jesus Christ, called to be an apostle, separated unto the gospel of God,
2 (Which he had promised afore by his prophets in the holy scriptures,)
3 Concerning his Son Jesus Christ our Lord, which was made of the seed of David according to the flesh;
4 And declared to be the Son of God with power, according to the spirit of holiness, by the resurrection from the dead: (Romans 1:1-4.)

Unless an LDS apostle was called by God to bear witness of the risen Lord by a personal visitation from Jesus Christ, they should not be using the title.

The title of apostle is not even used in The Book of Mormon.