everytime I start my PC and log in battlelog I must change theme (i use dark theme by Hille - mod by Juress) and set language. I´m using Chrome 23. I don´t block or delete cookies.
BBLog will lost the settings if you delete some browser-cache data. You must make sure that no automatic garbage truncate, private mode, auto cleanup is enabled in chrome. Also a tool that cleanup your pc from garbage can delete those browser data.
Here is something that may help you with configuration
This have nothing todo with cookies. A local storage is used to save data.
Most people that reported this problem have some wrong settings enabled.
I don't be able to help you in this case because it's a very specific problem that presumably depends on your configuration. Maybe try firefox or use the "cloud" feature of bblog to save/reload your settings if they lost.
I updated BBlog yesterday to v.2.6.0 and now all works fine.