This post shows you how to update all objects in a collection using Linq in C#.

For example:

foreach (var o in collection)
    o.PropertyToSet = value;

If you want to use just the framework you can do

collection.Select(o => {o.PropertyToSet = value; return o;}).ToList();

The ToList is needed in order to evaluate the select immediately due to lazy evaluation.

Another way

collection.ToList().ForEach(o => o.PropertyToSet = value);