Admin users can activate the ability to modify grids for certain users. If you cannot access a column chooser on your grid, you will need to ask your admin if you can gain access.
Admin users grant the ability to change grids:
Navigate to: Config > User > Double-click Choose 'User Name' > UI Views and Privileges > Company > General > and select User can Modify Grid Layouts. Save.
Once the user logs out of EnvioAg and back in, he/she should be able to modify grids.