It sounds as though FCP prefs have become corrupt. I suggest you download "Preference manager" from divergent media. Once installed run it then un-tick the checkboxes for everything except FPC7 then trash preferences and quit. Launch FCP then set up as you prefer. Use FCP for a while then if FCP is behaving itself, quit. Then go back into Preference manager and choose the Back up option. From there on, if and when things get a bit weird go to Prefs manager to trash then choose to restore your backed up working preferences.