There has been no change whatsoever to this part of the code in...
years ! So, if something changed, it's not because of a change in the Cool VL Viewer...
Obviously, if you clear those data, you also clear all the saved passwords...
And then you deduce that the problem is with the Cool VL Viewer instead of Singularity ?... Strange logic. If everything works fine till you use Singularity and then things go bad, I'd rather infer that the issue is with Singularity...
The saved login names/passwords are written and read by the Cool VL Viewer into/from the user_settings/saved_grids_login.xml file (it's saved_logins.xml for LL's viewers, and saved_logins_sg2.xml for SIngularity, so there should be no collision between these viewers: I chose a different file name, years ago, in order to avoid such collisions since the files are not formatted in the same way); if this file gets overwritten, corrupted or deleted, then only your last login name is remembered (it's saved in the viewer settings). I'd suggest you backup this file and watch out for when it gets changed/deleted and by which program, which is certainly not the Cool VL Viewer...