There are quite a few settings that can affect changes you make to reference level symbology, so I thought I would mention a couple of basics to check when changes do not save between sessions.
With the introduction of V8, a new setting was introduced called SET REFLEVELOVERRIDES. Despite the name, this does NOT have anything to do with Level Symbology Overrides. This controls whether or not the changes to any reference level settings are saved to the drawing or discarded when the file is closed.
I'm not fluent in AutoCAD, but I'm told this is similar to the AutoCAD VISRETAIN setting and (like the AutoCAD setting) has only two states - ON and OFF. ON means that any changes you make to your reference level symbology WILL save to the file. OFF means that all those changes will disappear the moment you leave that file. There is also the option to TOGGLE between values.
The setting can be checked by going to the Keyin dialog, typing in SET REFLEVELOVERRIDES (with no value) and hitting <Enter>. This will show the current value in the Message Center. To change the value, type in SET REFLEVELOVERRIDES (ON/OFF/TOGGLE) then <Enter>. Make sure to Save Settings.
OK...Now that we've made sure that our changes will save between sessions, we need to see whether or not our changes will get overwritten. This happens when the configuration variable MS_LEVEL_AUTO_SYNC_ATTRIBUTE_LIST contains the attributes we are trying to change. When levels sync automatically, they go right back to the symbology definition stored in the level library. I've heard that this can be better controlled in XM, but I haven't had a chance to really check that out. If any changes have been made to our reference level settings, autosync will reset them back to the standard. If reference level changes are needed, this configuration variable will need to be defined in a way that does NOT sych changed attributes.
Other variables that affect reference level alterations are:
Information on these variable can be found under Workspace -> Configuration -> Levels.
In the AutoCAD world, where many, if not all settings are set to bylevel, it is common to use the level dialog box to control the display and plot of reference files. In the MicroStation world, many people used to use level symbology to do a similar process, but now we can use either or both. But when used, it is usually a setting that is desired to be saved in the file it was made, not in the original file. In a multi-discipline project, you may need a reference file for a sheet that is not under your control, or may need to display the same reference in two different sheets using dis-similar symbology - so the changes need to stay in the sheet, not the reference.