create signature in Preview?

I cannot draft my signature in Preview.  

First I go to the Show Markup Toolbar.  Then I click the Sign button.  I get the dialog box that stays Click Here to Begin.  When I click that button, Preview places my cursor right in the middle of the dialog box. 

My problem is in lifting my finger off the trackpad.  I have been able, after several attempts, to write my first name in the space between the center of the dialog box and its right margin.  But then I lift my finger off the trackpad before writing my middle initial, and Preview resets the cursor back to the center of the window, where the first letter of my first name is.  Preview won’t let me move the cursor to the right, where my middle initial belongs. Preview insists on my drawing over what I have already created.  

I have no idea if I could finish writing my whole name in the window.  My first name takes up all the space between the center of the dialog box and the right margin.  I would hope that the window would move to the right if I were to write my middle initial and surname.  But I don’t know, because, as I say, I cannot insert the cursor to the right of what I have already written.

Is there some way of moving the cursor in the Signwindow without drawing a line where I do not want it?