In case of update, changes made to the PHP and database are deleted?

[OriyanJ]

I'm using VirtueMart 3.0.11.4 and I've made lots of changes to the in the PHP and databases (both at front-end and back-office).
I'd like to know that the changes I've made will always be safe.
In case of VirtueMart update, are they gone?

And if so, what can I do in order to save them?

[GJC Web Design]

they are gone

all files and db tables are "refreshed" on an update

[OriyanJ]

And how can I make sure they're saved?

[GJC Web Design]

use over rides...  read the docs....

[OriyanJ]

Thank you