While tuning your uke, stretching your strings is essential to ensure that new strings don't slip out of tune during a practice session.
Once you're in tune, slip your index finger beneath each string and give it a gentle tug upward. As the slack is let out of each string, it will naturally go flat. To correct this during the stretching process, always re-tune the string to standard pitch immediately after stretching.
Repeat this process several times prior to playing and you'll find that your ukulele stays in tune without slipping. Pls note that this happens on new strings, not an issue of the quality of our product.