Hi all. New user here. so please be patient with me, thanks.
How do I changing from a from a published theme to another brand new theme without missing out on any of the customization? I'm referring to codes that i have added for analytics. If that makes sense? Is it as simple as just cutting and copying the tag from the previous theme to the new one?
Not sure what kind of analytics you are referring to, but if you're not referring to Google Analytics, then yes, you would just copy and paste the tracking snippet to the new theme.
If you're referring to Google Analytics, there's no need to add a code snippet to your theme. Just add your Analytics ID (UA-...) into the appropriate field at Online Store -> Preferences and the appropriate tracking code will be dynamically inserted into the published theme.