I made a change but my blog is not updated
By default, b2evolution saves a cached version of all your public blog pages and only refreshes that cache every 15 minutes.
This is very handy in case one of your blog posts gets very popular, as it allows you web server to serve the page really quick to everyone who wants to see it and only regenerate it once every 15 minutes.
The potential downside is that if you make a change on your blog and then log out, it may happen that you still see the old version for 15 minutes.
The problem will fix itself if you reload the page after 15 minutes.
Note: b2evolution will never send you a cached page when you are logged in. Cached pages are only sent to Anonymous Users.
If you are making adjustments to your skin and this is preventing you from working effectively, you may turn off the page caching in
Collections > [Your collection] > Settings > Advanced (Caching)
There is one setting per collection. And there is also a setting for pages that are not part of any blog in Site > Site settings (Technical Site Settings). This one is only useful for large sites where you may have additional templates that are not part of a skin.
Note: for best performance, always turn caching back on when your have finished tweaking your site. In normal operations, you should never need to turn page caching off.
If you need more detailed information about cache and cache levels in b2evolution, please read: Caching and Cache Levels