find form controls in forms in current project

I don't understand exactly what you want. If you want to change the font in all of the TextBox controls in a solution/project, I'm afraid you're going to have to do that one control at a time in the designer. I'm not saying this because it's impossible to write another app that parses the source files for you, but because you have to SEE what the change is going to do in the form with ragards to the relative position of the other controls that are also on the same form (not to mention the form itself).

Now, if you want to programatically change the font on all of the tTextBox controls on a form, you can easily do that, but that doesn't preclude you from having to consider the same positioning and soize ramifications already described.

Lastly, a demand for code typically doesn't go over very well here, no matter how much of a code virgin you are. If you want to programatically change the font in a control, this is something like the way I'd do it:

private void ChangeFontInTextBoxes(Control container)
{
    foreach (Control ctrl in container.Controls)
    {
        if (ctrl is TextBox)
        {
            // set the font or other desired properties
        }
        else
        {
            if (ctrl.HasChildren)
            {
                ChangeFontInTextBoxes(ctrl);
            }
        }
    }
}

and I'd call it from the form like this:

ChangeFontInTextBoxes(this);

The code above uses recursion (google it).