Hello Rachel,

It seems to be a long version gap when you upgrade from 2012 to 2020 version. We have introduced a lot of improvements and new features regarding RadGridView and it is normal if some functionalities have changed since then.

Currently, RadGridView allows adding a FilterDescriptor programmatically through the FilterDescriptors property. It stores FilterDescriptors used for the filtering operation in RadGridView. You can create a new FilterDescriptor, specify its PropertyName, Operator, and Value properties then assign it to the FilterDescriptor's collection. Thus, when you start the form the applied filter will be initially loaded. More information about filtering functionality you can find here: https://docs.telerik.com/devtools/winforms/controls/gridview/filtering/setting-filters-programmatically-(simple-descriptors).

Please refer to the following code snippet:

public RadForm1()
{
    InitializeComponent();
    this.radGridView1.AutoSizeColumnsMode = GridViewAutoSizeColumnsMode.Fill;
    this.radGridView1.EnableFiltering = true;

    FilterDescriptor filter = new FilterDescriptor();
    filter.PropertyName = "Title";
    filter.Operator = FilterOperator.Contains;
    filter.Value = "Representative";
    filter.IsFilterEditor = true;
    this.radGridView1.FilterDescriptors.Add(filter);
}

private void RadForm1_Load(object sender, EventArgs e)
{
    this.employeesTableAdapter.Fill(this.nwindDataSet.Employees);
}

I hope this helps. If you have other questions do not hesitate to ask.

Regards,
Nadya
Progress Telerik