How have most constitutional changes been brought about?

Constitutional changes have been brought about by constant growth in society. It could be revolutionary’s or a mass of the population wanting and fighting for change.

For example: With the recent gun violence issues in America and such a high percentage of their people protesting, America could take a vote and begin to amend their constitution to appeal to the mass of their population. This showing that a growth in society is what’s ultimately behind revisions in the constitution.

The answer would be advertising.