To unsubscribe from the views, you should use the My Content area of Tableau web pages. This area allows you to manage your subscriptions, as well as your workbooks, views, and data sources. You can select the views you want to unsubscribe from, click Actions, and then click Unsubscribe. You can also change the subscription options, such as the schedule, the format, or the message. References:
* Create a Subscription to a View or Workbook - Tableau
* Tableau Certified Data Analyst Study Guide

The LAST() function in Tableau returns the number of rows from the current row to the last row in the partition. When you compute using 'Order Date', it will change the partitioning of the calculation. If
'Consumer' in '2018' is the last row in its partition when computed by 'Order Date', then LAST() will return 0 for that cell.
The LAST() function in Tableau is a table calculation that returns the number of rows from the current row to the last row in the partition. The value of LAST() is 0 for the last row, increases by 1 for each row above the last row, and can be negative for rows below the current row if there are such rows in the partition.
In the provided visualization, LAST() is set to compute using Table (across). Changing the compute mode to use "Order Date" will adjust the partitioning of the data upon which the LAST() function is calculated. Since
"Order Date" is likely to be a unique value per row (assuming each order has a unique date), each row becomes its own partition.
For the Consumer segment of the year 2018, if "Order Date" is unique for each row, then the last row in each partition (in this case, each individual row) will have a LAST() value of 0 because there are no other rows in the partition - it's the last row of its own partition.
Therefore, when you change the compute mode of LAST() to use "Order Date", each cell under the Consumer segment for the year 2018 will have the LAST() value of 0, because each order date creates a partition of one, making every row the last in its partition.

To customize a layout for mobile users, you should select the Device Preview option first. This option will allow you to see how your dashboard will look on different types of devices, such as phones, tablets, or desktops. You can also choose different models and orientations to preview different screen sizes and resolutions. From the Device Preview mode, you can add, edit, or delete device layouts for each device type.
You can also adjust the size, position, and formatting of the dashboard elements for each device layout. References:
* Create Dashboard Layouts for Different Device Types - Tableau
* Tableau Certified Data Analyst Study Guide