I installed WP using Fantastico and began fiddling with the header and footer files in the default theme, customizing the theme to embed withing the rest of my website. Then I saw a notice in my dashboard that there was a newer version on WP and I should update to the latest version. I really appreciated how easy it was to update my version, but after doing so all my theme customization was reverted.
Is that going to happen every time I upgrade to the latest version of WP?
How is this avoided?
Did this only happen because it was the default theme that I had customized?
If I customized an installed theme would I be safe to update in the future?
I haven't experimented with widgets yet but would those all get messed up to every time I update WP?
I'd just hate to put all this effort into making the blog exactly the way I want it to look and then have it wrecked every time a new version came out (or I couldn't update it).