Upvote:1
As Barcelona and Madrid are both in Spain, changing the airport will not make much of a difference.
Only if you had to give details for each day of your stay, including hotel reservations, you may get asked about the change in your plans. And with that kind of detailed plans you best not change anything.
The change in date is more important.
Whether that is allowed depends on how the dates on your visa are given. If the dates are given as 'so many days in a longer period' and your new dates fall in that longer period, you are OK.
But if your dates are just covering your old plans you will need to apply for a new visa for the new dates.
If you can give us the details of your visa, like the valid from-to, the number of days, and any other restrictions printed or written on it, we might be able to help you better.
Please edit the information into this question and not as a new question.