Any user can set a minimum security level for all future entries. For example, setting this option to Friends-Only or Private will prevent you from accidentally posting a public entry that you meant to post at a protected level.
Set the minimum security level of all future entries in your journal at the Viewing Options page by selecting the appropriate option from the Default privacy of new entries box.
It is also possible to set the minimum security level of all future entries in your journal by typing the following Admin Console commands:
set newpost_minsecurity level
Apologies if I've pooched this suggestion, it's my first one, and I only thought about it 'cause I dropped into support for the first time in forever and found a question about it.