Why aren't my SEO changes reflecting on Google search?

[AlexB4]

Hello - am new to building websites with Shopify so please bear with me!

I like the overall look and design of my website but there are a few niggles.. For example when I search for my website on Google a couple of the SEO's are wrong. When I go into pages and try to update the SEO text it doesn't change and instead comes out with garbled nonsense. Does anyone have any idea why this might happen?

Also the top drop down is Products which doesn't actually have a listing in my pages.. I can obviously see my products page with the various products I sell but can't adjust the SEO or even remove it from the google search of my business.. 

website is - www.letsmix.co.uk

Any help would be greatly appreciated and happy to pay someone that can potentially help me!

Alex