Compaq t1000 - Terminal Thin Client PC Quick Reference Manual page 14

Write Filter Cache
If changes have been made to the system configuration settings, that
you want to persist, you must flush the write filter cache during the
current boot session. Otherwise the new settings are lost when the
terminal is shut down or restarted. The write filter cache contents are
not lost when you simply log off and on again (as the same or
different user); that is, you may flush the write filter cache after the
new logon and still retain the changes. See the write filter topics later
in this guide for instructions on how to flush the cache.
Quick Reference Guide 11