Macro to hide/unhide columns in multiple worksheets and protect/hide on close

[nfs001]

Hello

I have limited knowledge with macros so would appreciate any advice you can give me.

I have a Workbook that has several users - most only need to view the Workbook, others need to edit certain columns. I would the columns that need to be edited hidden on opening and only visible once you have unprotected/unhidden them. I don't want anyone to just be able to open the Workbook and unhide the columns, so I'm guessing I need to password protect the Worksheets?

I have 4 Worksheets in the Workbook that contain identical data on each sheet (worksheets are called "2018", "2017", "2016" and "2015"). I would like columns I and L to be hidden on all sheets when the spreadsheet is opened and only unhidden when they need to be edited by certain users. I don't mind if columns I and L are unhidden on all 4 Worksheets at once.

I'm also slightly concerned that a User could accidentally save the Workbook without re-hiding the columns after they have made their changes so I'm not sure if there is a way to hide/protect the document automatically on close/save?

Hope this makes sense.

Thanks!