DHH here is the quote from the 1995 yearbook
La Torre del Vigía de México—A Cultural Society
"You will recall that back in 1932 La Torre del Vigía de México had been authorized by the government. However, there were obstacles because of the restrictions that the law imposed on all religions. Objections were raised to the house-to-house activity of the Witnesses, since the law stipulated that ‘every religious act of public worship must be held inside the temples.’ For the same reason, objections were raised to our conventions in public places. This was a problem, because these conventions were constantly getting larger. Owning property also presented problems, because the law required that every building used for religious purposes had to become federal property.
For these and other reasons, the Society decided that it would be wise to reorganize, with a view to giving greater emphasis to the educational nature of our work. Therefore, on June 10, 1943, application was made to the Secretariat of Foreign Affairs to register La Torre del Vigía as a civil society, and this was approved on June 15, 1943.
With this rearrangement, singing at our meetings was discontinued, and the meeting places became known as Halls for Cultural Studies. No audible prayers were said at meetings, though nothing could prevent a person from saying an earnest prayer silently in his heart. Every appearance of a religious service was avoided, and truly our meetings are designed for education. When Witnesses in other lands began to call their local groups “congregations,” the Witnesses in Mexico kept on using the term “companies.” House-to-house visits by the Witnesses continued, and with even more zeal; but direct use of the Bible at doors was avoided. Instead, publishers learned the texts by heart so that they could quote them. They also made good use of the book “Make Sure of All Things,” which is a compilation of Scripture quotations on many subjects. Only on return visits and on studies (which were termed “cultural” instead of “Bible”) was the Bible itself used.
The principal work of Jehovah’s Witnesses remained the same, namely, preaching the good news of God’s Kingdom."