You are managing a SQL Server Reporting Services (SSRS) instance in native mode. A system role named Developer Support is present on the server. Members of the Developer Support role cannot modify the

Execute report definitions allows users to run ad-hoc report definitions uploaded directly, and has no relation to modifying server-wide timeout properties.

Manage shared schedules controls creation and modification of shared report schedules, not server configuration properties like execution timeouts.

Manage jobs allows cancellation of running report jobs but does not provide access to server-level configuration settings such as execution timeout.

The 'Manage report server properties' system-level task grants the ability to view and modify server-wide settings including the report execution timeout, memory management thresholds, and logging options. Because the execution timeout is a global server property - not a per-item setting - it can only be controlled through a system role task, making this the correct task to assign.