Easy to Tune
The standard C tuning features strings tuned to G, C, E, and A(From the left to the right when you put the ukulele straight and facing the front as the left picture shows). You may begin your tuning with the 3rd string, which is the note C, the G-E-A.
For a new instrument, it will take time for the string as well as the ukulele body to adapt to the pulling force. You may need to tune the ukulele several times until the force is balanced and the tune is settled.