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
Meet Neat — our latest Shopify themes.
Neat Shopify
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- Getting started
- Sections
- General settings
- Settings overview
- Setting up navigation
- Fonts, colors
- Working with templates
- How do I set up swatches?
- Image and video size recommendations
- What is lazy loading?
- How do I set up a product size chart?
- How can I create my own custom pages with sections?
- How can I create my own custom product pages with sections?
- Installing Shopify’s Product Reviews app
- Using the currency converter
- How to enable sticky add to cart
- How do I add product videos?
- Why won’t my videos autoplay?
- How do I remove “powered by Shopify” from the footer?
- What version do I have?
- Product scrolling text sales
- Advanced settings
- How can I enable product filtering?
- How do I update my theme?
- How do I show images only for a specific color?
- Variant Images Grouped
- How do I remove the shopping cart?
- How can I improve my Online Store speed score?
- How can I customize my checkout and cart?
- How to set content in a tab differently in each product?
- How to set up Mega menu
- Home
- Docs
- Neat Shopify
- Advanced settings
- How do I update my theme?