The provisions of this chapter shall not be construed to devolve any additional powers upon county councils with regard to public school education, and all school districts, boards of trustees and county boards of education shall continue to perform their statutory functions in matters related thereto as prescribed in the general law of the State; provided, however, that except as otherwise provided for in this section the county council shall determine by ordinance the method of establishing the school tax millage except in those cases where boards of trustees of the districts or the county board of education established such millage at the time one of the alternate forms of government provided for in this chapter becomes effective. In counties containing more than one school district, where all such districts are located wholly within the boundaries of the county, council may by ordinance establish county-wide school tax millage. Provided, further, that in any county where the General Assembly retained the authority to establish or limit the millage levied by school districts or levy a tax for educational purposes, on January 1, 1974, such authority shall continue in the General Assembly until such time as such authority may be transferred to the school district or the county governing body by act of the General Assembly. Provided, further, in any county where on January 1, 1975 the school district tax millage and budget was established in meetings or referendums of the qualified electors of the district at which meetings or referendums such electors changed, altered, rejected, or amended by voice vote or ballot the school budget and necessary tax millage to implement such budget as proposed by the district board of trustees, such procedures to establish the school tax millage shall continue unaffected or modified by the provisions of this section or any other provision of law in conflict with this proviso.