Section 25. A society entering into insurance agreements under section 23 shall maintain on all such contracts the reserve required by the standard of mortality and interest adopted by the society for computing contributions as provided in section 24. The funds representing the benefit contributions and all accretions thereto shall be kept as separate and distinct funds, independent of the other funds of the society, and shall not be liable for nor used for payment of the debts and obligations of the society other than the benefits authorized in sections 23 and 24. A society may provide that when a juvenile member reaches the minimum age for initiation into membership in such society, any benefit certificate issued under sections 23 to 28, inclusive, may be surrendered for cancellation and exchanged for any other form of certificate issued by the society. If it does not mature or expire prior to the attainment of such minimum age, any such benefit certificate may, notwithstanding any limitation in section 23, be continued in force, if in either case, such juvenile members shall present themselves for initiation as provided in the society’s by-laws relative to the admission of adult members. All reserve accumulated under the certificate prior to the admission of any juvenile member to adult membership shall be transferred to the adult department to the credit of the transferring member. After the transfer of membership, the member shall have the sole right to designate a beneficiary, subject, however, to the by-laws of the society.