How change the "Sol key" to "fa key" on the same partition ?

Sorry, i'm not very good in english, hope you understand me

Hi... i have to write a partition but for the 10 firsts mesures... with keybord... my two hand work with "sol key" (G)... but after this... the right hand continue with the G key but my left go with the F key... but when i try to change the Key... all the partition change ... can you help me please

ok forget it... I just find It...