You can update the theme follow as Shopify guidelines. This link has detailed steps for you to upgrade the theme easily.
This is the link: Updating themes
Punk
⌘K
- Getting started
- Sections
- General settings
- Fonts, colors
- How can I create my own custom pages with sections?
- How can I create my own custom product pages with sections?
- How do I add product videos?
- How do I remove “powered by Shopify” from the footer?
- How do I set up swatches?
- How to enable social icons in the footer
- How to enable sticky add to cart
- Image and video size recommendations
- Product scrolling text sales
- Setting up navigation
- Settings overview
- Using the currency converter
- What is lazy loading?
- What version do I have?
- Why won’t my videos autoplay?
- Working with templates
- Advanced settings
- Home
- Punk
- Advanced settings
- How do I update my theme?