I am working on adjusting my project plan in MS Project and I need to change the end date on a task without affecting the dates on any of the other tasks?

assuming this task is linked to other tasks with a FS relationship, change the successor logic to SS.

E.g. if the task you want to extend its finish date is ID3 and its successor is ID4, in the successor column of ID3, enter, 4SS.

=jerome
plannersplace.com

It is currently linked with a SS and is linked to a milestone. I am basically trying to push the end date of the task without affecting the other dates in the milestone.

Only other option that comes to my mind is to break the link to the milestone and apply a "Start No Earlier Than" constraint to the milestone.

Can you describe the task chain and what you want to change and what needs to be protected? This might allow us to help more?
Do you have the true relationships in the plan (i.e. this can't start until this has finished) rather than time relationships (I'd like to do this and then move onto this)? If you've got the former sort then the plan can tell you the true consequences of change. The latter usually ends up being a pain in the backside as people change their minds about the order they'd like to do things