ThreeKeys.....I would guess we have all been told, "You've changed." at least once by someone in our life. If the person who had made that comment does not add their reason for saying it, this can lead us to assume any number of things:
It's always possible that person's "perception" of you is different at a certain time under particular circumstances. Perhaps we truly have changed in some drastic way, intentionally, for our own personal reason & can be pleased that it's noticeable. It's also quite possible the person saying you've changed is in fact the one who has changed but unwilling to admit this.
In any case, if that comment is something you feel the need to understand, it would require further discussion and some questioning. For one thing, exactly what about you do they see has changed? Your appearance? attitude? behavior? beliefs?
Hopefully, as we move through life we all change by growing, learning & discovering new and different aspects of the huge world around us. I firmly believe we are different today than we were just yesterday and will be different again tomorrow and all days to come.
We're not programmed robots, thank goodness. We have every opportunity and quite often good reason to change our minds on any topic we can name. People can change, do change and certainly there are some things we should want to change about ourselves, our lives and things we may have believed for years.
If we feel in our heart that the changes we've made are to our benefit and that of those in our life, it can only be positive. As for "why" someone may mention to you that you've changed.....that's pretty much for them to explain.