Parameters & Line-Graph Hierarchy Retain Position

Good morning, 

Looking for a little bit of help - first time poster.

I have a project for which I have created two sets of field parameters. 

The parameters are "Calendar Year" and "Financial Year". 

They are linked to a data dimension table, with one set of parameters linking to the 'month' columns and the second set of parameters linking to the 'year' columns. 

I have created a relationship between the parameter names and have one slicer which displays "Financial Year" / "Calendar Year". 

I have a line graph which displays both the linked year & linked month on the x-axis. 

(Both SelectedYear and SelectedMonth are text types). 

I have tested and this works fine, however, when the parameter is changed, by default the line graph reverts to the highest level (ie. the year). 

If I press the "expand all down one level in the hierarchy" button, then the graph displays as I would like it to - split by month / year:

However, importantly, when I change the parameter - this defaults back to the first level in the hierarchy. 

I have tried bookmarks but can't seem to get that to work either.

Is there any way to set this visual to display with the expanded hierarchy as default? 

Thank you