Parameters

Parameters in Tableau for Confluence - Pro allow you to filter data that is used within the datasource that is used in the view. See: https://onlinehelp.tableau.com/current/pro/desktop/en-us/embed_structure.htm#select-an-example-view-to-work-with for a bit more background. You can also see more documentation on Tableau Parameters at Create Parameters

Parameter values in a Tableau workbook are static user-input variables, and they do not operate the same way as dimensions. They only contain one value, and dimensions in the workbook contain a set of unique values that exist within the used datasource.

In short, Parameters on a Tableau dashboard will have to be adjusted within the workbook itself once it is loaded and the value of the parameter cannot be adjusted via the Tableau for Confluence Pro Parameters field. 

For example you had a datasource with Parameters called "Year" and "Month", you would do something like this:

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