What are the advanced setting used for?

The advanced setting (under Settings -> Advanced settings), change a number of defaults used by Cloud Xtender. The following details what these are, and how they affect the underlying files. One thing to note is that these setting are global, and will be applied to all relevant files.

Meta cache size (affects remote sync'd files only)
When a remote file is cached, the cache is flushed after a pre-set period, (this period can be set via the file''s placement rule). Using this setting you can permanently retain a small amount of the cache to improve Windows Explorer performance. This is more relevant for some file types, and not so much for other. For example, a music or video file contains quite a lot of metadata, as opposed to a text file, which may contain no metadata at all. When Windows Explorer, or some other third-party plugin tries to access the metadata for a given file, Cloud Xtender pulls this from the cloud service and caches the information. Some time later, an internal scheduled task then clean up this cache. Using this value you can explicitly tell Cloud Xtender that you want to retain a maximum of this cache for later use, this will minimize cloud storage access should this same metadata be required again.

Limit Windows caching to this amount (affects remote sync'd files only)
When this setting is enabled, any caching that is performed by Windows itself, is limited to that same "Meta cache size" value as specified in the previously setting. For example, as per the image, this cache size is set at 128KB, meaning that when Windows probes a music or a video file, the maximum amount of data it can pull from the cloud for these files is limited to this value.

Checking remote file (affects mirror and remote sync'd files)
If a file is not using bi-directional monitoring (aka the remote file is not monitored for any changes), this value determines how often the remote version of a given file will be checked regardless. By default if a files is not using bi-directional monitoring, then the remote version of the file is never checked for changes. However you can still have these files checked on a limited basis using this value. Note we do not recommend using this to monitor remote files, if you know a given file or files will be changed on the remote storage service, then you should set up a bi-directional placement rule.

Retaining "Locally cache files" (affects remote sync'd files only)
Remote files that are cached locally using the "Cache locally for a limited time" option (right clicking a remote file will display this option), will remain local for a given period. This value determines this period. Once this period is expired, the files is sync'd according and local version is then removed form the system. Note - This is the minimum period, the cached file may remain for a longer period as the internal scheduled task that performs the clean up only runs once a day.