Personal changes can help but globally there needs to be many, many personal changes to make a significant difference. Those individual changes are best achieved under an umbrella of common purpose to create focus.
One person or a few individuals changing from a less-efficient to a more efficient form of heating or cooling will have an imperceptible effect but 500,000 changing similarly over a short time would result in a major and measurable difference.
Such, and many more, are the changes humankind will need to make to achieve a significant, observable improvement to this planet's climate. The effect of a few individuals here and there gets lost in background 'noise'. Governments need to co-ordinate such changes, ideally with countries and nations adopting similar co-operative approaches.
Given humankind's long history of non co-operation, things don't look altogether promising.