Dropdown list and Text field not populating an HTML table when selected

I am trying to populate some table cells after the user selects a month from a JavaScript drop-down list and enters a year in a text box.For some reason the form is not working. As an example when I select a month, nothing happens. Similarly when I enter a year.

For the month dropdown list, the user needs to select a month from a drop down list.
For the year text field, the user needs to enter a year in the text field.

The year entered in the text box should populate the year (column 2) in the table. The month in the dropdown should populate 2 cells in the first July and October instances of column 3 as either the year entered, year + 1 or year + 2 for the various months in column 1.

Please see this table screenshot that shows what I am trying to create.

Depending on the month that the user selects, the ACWB 3rd table cell will be populated with Trustee or recipient (e.g., January-June = Trustee and July-December = Recipient

For the ACWB 4th table cell depending on the month that the user selects, will be populated with Trustee or recipient (e.g., January-September = Trustee and October-December = Recipient

The first section of the code below, will appear in the head of the HTML page. The second section of code below will appear in the body of the HTML page. Hopefully, this is clear but if not, please contact me to ask questions.