You say you don't know to get them tight try this.
1. Unscrew the shift **** and remove the shift boot and console cover plate assembly. (Push your fingers into the boot, hook your fingers under console plate and lift up).
2. Remove the factory shift handle with a 10mm wrench.
3. Remove the four bolts (8mm) holding the inner rubber shift boot plate and remove the boot.
4. Tighten the four bolts (13mm) holding the factory shifter to the transmission.
And if that doesn't work it's either the bolts are stripped that hold the cover to the transmission or the transmission has no threads for the bolts to grip too.
Mustang Monthly Jan 2015- Feature
5.0 Mustang & Super Fords July 2005