BP 639 long ext to changed Message

Dear Friednds,

How can we change the stnadard long text .

For example , we have activated Fund management ,when ever we run the FI trnasaction , system gives one standard message budject is exceeded actully this is long text defined in BP message class message number 369.

But we need to modify this text to our custum message.

Here object is referring BP369. ID is NA how can chage this .

Please give me suggesations