Bring your symbol window up.
Make your symbols.
In symbol window hit the + to save it as a symbol.
Save your symbols, bot left of symbols window hit the books and hit save symbols.
Save it in the default symbol folder
To open hit those books again in the lower left, hit User Defined, and choose the file you saved it as.
To keep it there hit the 3 horizontal lines at top right and select 'persistent'.