How to upgrade the theme when new update comes out?

Fastest way tutorial

Official Shopify tutorial

Here is an official tutorial so you can understand more clearly. At the bottom there is also a a paragraph with title “Is there anyway to avoid re-customizing my theme from scratch?”

Manual update

(without copying code in settings_data.json file)

  1. Copy all your images from assets folder of the current theme you have, to our new theme, before uploading (Shopify just override default theme images with the image you upload so they have a same name). Otherwise you would need to upload home, slider, banner and parallax images again.
  2. Open theme customize of your current version in one browser tab, and then open the theme customize of the new unpublished theme (the new one with updates that you just uploaded) in the second tab and then check the settings and copy paste text etc. Once done you can preview new theme (small eye icon next to unpublished theme) and see how it looks before going live with it. It should take no more than half an hour of your time, depending on which theme settings you are using.

shopify-preview-theme