DefaultBufferMaxRows is not changing in ssis

Can any one tell,what is the reason the DefaultBufferMaxRows is automaticaly changing to 10000 when i run the package through BIDS.My package contains only one source,lookup,destination tasks.total 100000 records i want to insert into destination table by doing lookup to same destination table(non matched record).total 5 columns are passing,all are the type of int.
Actually i have increased the DefaultBufferMaxRows to 50000 before running the package and all other settings are default.What is the reason?

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