Question

Why am I unable to make any changes to the PO Table using Manage Columns?  The changes I am making don't seem to stick.  

Answer

This may be happening because a column is enabled that your buyer company is not using.  For example "Approved Date" is often enabled by default.  Try turning that column off and saving that change.  You should be able to adjust your columns after this fix.  Please reach out to support@sourceday.com if this does not work.