The time period in the content tab is displayed in the top right corner and will be based on the last 30 days prior to the creation of the report.
You are able to request an update of the 3 selections (liked, shared, influential). This means that the content tab will deliver you data from the last 30 days since when you refreshed the tab. 48 hours is needed since the last generation before you can request it again, during this period the refresh button will be disabled. In our roadmap, we plan to allow you to export the data from these content selections.
The data displayed does not change when you change the baseline, because the content is based on the audience members that you are viewing, and their behaviours as they are in themselves. You will still see the content vary between the segments and the full audience.