You are quite right about “the old days” – much simpler in some ways.
In today’s world of computers though, I suggest the following:
1. At a duly constituted meeting, agree that the minutes need to be altered and authorise the Secretary (you) to make the alterations of the original minutes document on the computer.
2. Record that decision and the authority to change the document in the minutes of THAT meeting – where the decision to change is made.
3. Go back to the original document – make the change and highlight it with a comment that this alteration was made later following a decision made at the meeeting of (date)
4. At the next meeting, report what you did and provide a copy for the chair (and anyone else) to see what you did.
That way there is a clear path of action and you, nor anyone else, can be accused later of altering the minutes inappropriately.
I hope that helps.
Please Note: The author accepts no responsibility for anything which occurs directly or indirectly as a result of using any of the suggestions or procedures detailed in this blog. This is not, and should not be taken as legal advice. The author is not a lawyer. All suggestions and procedures are provided in good faith as general guidelines only and should be used in conjunction with appropriate advice relevant legislation, constitutions, rules, laws, by-laws, and with reasonable judgement. If you are in any doubt, seek appropriate advice.