Hi Venkitta,
Yes, you can select only ONE portfolio at a time in 'Synchronize portfolio investments' job.
You need to create 20 Jobs and schedule if you have 20 active portfolios.
I have other option. I don't know it is better for you.
You can create process which invoke 'Synchronize portfolio investments' jobs 20 times for every active portfolios.
And you will schedule it by using 'Execute a Process' job.
'Sync Schedule' option of portfolio General section will invoke 'Synchronize portfolio investments' job automatically with that portfolio.
If you click 'Sync Schedule' option in portfolio_A, 'Synchronize portfolio investments' job that portfolio_A is selected will be invoked automatically.
If you want to schedule it once a day, 'Use UNIX crontab entry format' maybe easy for you.
For example, '05 5 * * *' will schedule job at every day am 5:05.
Regards,
Shoichi