By default, Burp remembers all configuration options when you close Burp down, and restores these when Burp is next run. You can modify this behavior via the following items in the Burp menu:
The options panels throughout Burp have "Restore defaults" buttons that you can use to restore default settings for individual panels.
You can also use the Save and restore state functions to save and restore configuration options. These functions lets you save state files containing settings for particular situations, and restore these when required.
Get help from other users, at the Burp Suite User Forum:
This release fixes a bug which was introduced in the v1.5rc2 release, and which caused the active scan checks for XSS to fail to execute in some situations