Please save your lexicon under a new file name.
It is important to save the lexicon, because it contains not just new words that you have used recently, but also information about your writing style that improves the quality of prediction, and your preferences.
If you open a lexicon which cannot be saved under the same name, normally because it is 'read only', then you should save it under a different name. Penfriend XL will then remember that and re-load the same lexicon later, unless the Load previous lexicon is switched off in the Advanced Options Dialogue box
If you have several people using this computer, each should have their own lexicon. It can be useful to have each person's lexicon saved on the desktop and the Load Previous Lexicon option switched off in the Advanced Preferences Dialogue box. Then when they click on their lexicon and start Penfriend XL they will recommence exactly where they left off and with all their own preferences.
Your preferences are automatically saved when you save your lexicon. Each lexicon can have different preferences thus a French lexicon can be saved with a French voice whereas a German lexicon would need a German voice. They can also have different colours, font sizes etc etc.