When Arechederra came to the Philippines one of his initial position was to become one of the four superintendent-commissaries appointed by the Holy Office of the Inquisition to assist Inquisition in the islands. During his time, Filipino natives or Indios were exempted from the Inquisition, for example, when a Spanish mestizo named Jacinta de Jesús was to be charged, she was acquitted by Arechederra by proposing herself as an Indio. In 1724, he accelerated the Inquisition charges filed against Antoine Guigue, a French missionary based in Guangdong convicted of Jansenism. He was later sentenced to be suspended from priestly actions and perform spiritual exercises until he appeased the Pope. In 1745, the Bishop of Nueva Segovia Manuel del Río died from office and Arechederra was elected to occupy this position. By July 1745, he assumed the diocese in full capacity while waiting for the Papal Bull proclaiming him as the new bishop. However, Governor-General Gaspar de la Torredied in office on September 21. By virtue of a royal decree issued earlier in August 15, 1734, in case of death of the governor-general, the highest governing person in the Islands shall take the responsibility of running the government. The same day, he assumed the position of being the governor-general and president ad interim of the Real Audiencia. Having heard of his acceptance as the bishop-elect of Nueva Segovia and his inauguration as the new governor-general, a letter coming from Madrid presented Arechederra to the King of Spain in 1750. In return the King ordered bulls recognizing Arechederra as the new Bishop of Nueva Segovia and affirming his position as the governor-general. However, on November 12, 1751, he died at office without having reached the bulls consecrated. During his short reign as the governor-general, he alternatively ruled in his diocese in Nueva Segovia and the government in Manila.
Baptismal of Alimuddin I
On January 2, 1749, Arechederra welcomed the Sultan of Sulu Azim ud-Din who sought refuge to the Spanish colonial authorities. Alimuddin I was previously ousted from his position as the sultan in a coup staged by his younger brother, Bantilan who seized the throne. Instead of publicizing his own intention of his refuge, which is to seek help in restoring him to power, Alimuddin I asked Arechederra to baptize him and embrace Christianity. After the examination of two Jesuit priests, he was recommended to be baptized. On April 29, 1750, baptisms took place at Paniqui, Tarlac. He was renamed as Don Fernando de Alimuddin. His children were educated in Spanish and Catholic education. Before fully pushing his ideals to restore him to power, Arechederra was replaced as a governor-general by the Marquis of Brindisi.