What governs backup frequency and how can I change it? (WD5000H)

I had an issue wherein the WD Backup was not capturing both hard drives on my machine but that seem to be resolved.  However, the log shows the last backup was performed 13 days ago.  Is there a setting I can change to increase the backup frequency?

I am totally new at this backup business and the online “Help” does not seem to address this issue.