I have the same problem.
I have followed the instructions to change the background colour in Greek Yoghurt using the customise button in themes.
When I hit the preview button I see my changes just as I want them. I have clicked on save and on activate but when I return to my website, the background colour has not changed from white.
I am I missing something or does the save function need fixing?
Many thanks,
Simon.

Are you sure your not just having caching issues? Try clearing the cache (Dashboard -> System and Settings - > Clear Cache) and hit 'Ctrl+F5' on your browser.

During development, I turn off C5's caching (Dashboard -> System and Settings - > Cache and Speed Settings) and also turn off caching in my browsers. Hitting 'CTRL+F5' in your browser works 95% of the time to reload a new page but I've found I need to turn off the browser cache completely while developing my sites.

Thanks for your advice.
I followed your suggestions to the letter, but still my colours do not appear.
Simon.

I'm not sure what's going on with the Greek Yogurt theme. I hope you haven't given up on it. I'm fairly new to C5 (6 months) and I don't use the customization options that are built into some themes so this might not be the proper way but I was able to fix this problem by moving all the customization css out of the typography.css file and moving it into the main.css.

First of all, if you haven't done so already, you need to copy the whole Greek Yogurt theme folder from {root}/concrete/themes to {root}/themes so you can make changes to these files without making changes to the original core files.

I have attached 2 modified files (main.css and typography.css) that you can insert into your new greek_yogurt folder. If you have already made some manual changes to either main.css or typography.css, then you will need to apply my changes to your files by copying any definitions in typography.css that have "/*customize_" in them and pasting these definitions into main.css. When you're done copying these definitions, delete them from the typography.css file.

As I say, this is a workaround to get past some odd behavior in the greek_yogurt theme. I'm sure what I am suggesting is not perfect and it probably affects the styles that show up in the content editor. If anyone in the community has a better fix or knows that what I propose is a poor solution, please feel free to school me.

On a different topic...

When I first started using C5, caching issues drove me absolutely crazy. I develop mainly with the Chrome browser and it's tricky to get Chrome to turn off it's internal cache so I have made a special shortcut on my desktop for Chrome and added this command line switch to the end of the shortcut's 'Target' field (leave out the quotes): " --disk-cache-size=1 --media-cache-size=1".

When I'm using chrome to develop a site, I open the browser with this shortcut and the browser's cache is turned off.

In IE, I go to "Internet Options -> Browser History -> Settings" and make sure "Every time I visit the webpage" is selected instead of "Automatic".

In Firefox, I go to "Tools -> Options -> Advanced -> Network Tab" and turn the cache limit to 0.

Also, I read elsewhere in the forums that turning the C5 cache off (Dashboard -> System and Settings -> Cache and Speed Settings) stops your customizations from showing up in the preview window until you click the 'Save' button so you can turn the C5 'Basic' cache back on if this is important to you. Leave 'Full Page' caching off however for development work.

Thanks again mhawke.

I left it overnight and resumed editing the next day. While I was moving a block around my background colour suddenly updated.

The only explanation I have is that I had prayed about it...

Thanks again for your generous sharing of your knowledge and help.

Simon.