Sol's memory is a distilled summary of your conversations - not a perfect record. It will sometimes be incomplete or slightly off. That's normal.
Just tell him
The simplest and most effective approach is to correct him directly in conversation. Sol will take the correction immediately, without resistance, and adjust his understanding of your situation accordingly.
Requesting a fresh start
If Sol's memory feels so far from your current situation that correcting it feels harder than starting over, the memory reset option is available.