After starting up Writer or Calc the color palette is set to "Standard", the color to dark red and the background-color to yellow.
No matter what palette, color or background-color you set while working, after a restart of the application all these things are reset to default. Also the last used color is not remembered between sessions.
It makes no difference if the same document is used or a new one.
LO should remember these settings between sessions. Also, this should be done independently from the document but rather as an application setting.
Thanks for reporting. Let's merge it with Bug 72991.
*** This bug has been marked as a duplicate of bug 72991 ***