Hi Lakshmi,
In SPRO->Governance, Risk and Compliance ->Maintain Configuration Settings no parameter is available for Default System in Risk Analysis.
However if we maintained default rule set (parameter - 1025 Default rule set for risk analysis) and if rule set is having risk specific to system only which you want to have default, then it will show the report of risk for required system only even if you keep the system blank at initial screen of Risk analysis Report while giving user details.
In this way whenever you will run Access risk analysis for any user you will just have to insert user id and keep system blank (by default) the rule set will get automatically filled with same value which we maintained in SPRO setting (1025 parameter) then risk report will be shown for system only which you want to be default.
Note - Rule set must have risk of the system which you will need as Default system.
Regards,
Rakesh Kirve