My name is Rae and I work for Shopify. I'm happy to lend a hand with this!
To change that text, please log in to your Shopify admin and follow these steps:
For reference, this is the field you'll want to edit:
In order to change the color of the green bar that this message appears on, we may need to change a setting within your theme. To check this, just follow these steps:
However, it's important to note that changing this green color in your theme settings will change it everywhere that it appears on your theme. So, if you only want to change this color in this one spot, you may need to customize your theme to complete this change. If you're using a Shopify-developed theme, our team may be able to help out with this. But, if you're using a third-party theme instead, it's best to speak with your theme developers directly about making this change.
With that in mind, can you please let me know which theme you're using? You can find this information directly in your Shopify admin under 'Online store > Themes > Current theme'.
I hope to hear back from you about this soon!