I've made a few changes to my theme and template files, added adsense into the theme etc etc. I want to upgrade, but I don't want to have to re-add all of my customizations. I went to appearance > styles> export to the default theme and the child theme I'm using. Is this enough to save my changes to all template files? Then I can just overwrite them once I upgrade with my backup and it'll bring back my customizations?