Follow these steps to view only your teammates and not everybody when using Quantify gadget.
In order to achieve this, you will need some advanced JQL
1. Create a new Jira filter called "my-team" to define teammates
assignee was in (Person A, Person B) OR creator in (Person A, Person B)
Depending on your workflow you may keep only assignees
assignee was in (Person A, Person B)
2. Use this filter with any other JQL statements
Yes, Jira can do that, you can reuse filters and combine them together using filter statement
type=Story and filter=my-team
It will return tickets with type Story where assignees/creators are part of your team.
3. Bonus part
Nothing prevents from using multiple filters in one JQL. Imagine, that you need to compare different teams based on the same criteria.
filter=bugs and filter=team-alfa
filter=bugs and filter=team-beta