What do multiple reports listed in a single SSRS report mean?

Question

I have one SSRS report like following (image)

I'm new to SSRS; what does this report mean?

If I need to change any parameter value for this kind of report, do I need to go to every report and change the parameter for them individually?

Answer 1

Question:
What does this SSRS report mean?

Answer:
Portfolio dashboard = Main report
Portfolio_XXX = all 8 are subreports.

The subreports may or may not link with the main report. To find the report link, you can right-click on the subreport (gray) then report link.

Question:
Do I need to go to every report and change the parameter for them individually?

Answer:
If you are changing parameter name/type and subreport are linked or use parameter to filter the data, then YES you have to change in main report and subreport.