Greetings, Make sure the auto scroll lock is checked, this should be found in the view menu, note I am still using V5.70, if you are using V6.anything, I am unaware of any possible changes.
Whilst playing the file, do control with g, in an edit box, it shows current cursor position at the time you issued the command, overwrite (or modify) and press enter, cursor jumps to the place given or if outside the file, gives an error and invites you to correct and re-enter.