Why can i not bevel this?

[tj251531]

I cannot select all the edges at once on the top half of the boolean, along with this unable to get a bevel. Im trying to build this harry potter train for my degree but for the life of me i cant figure out how to create indents into a cylinder without it changing the cylinders roundness.

Thanks

[damaggio]

Just select the edges on top and bevel, although this approach is not needed for this model and your topology is incorrect.