Change element attributes not working properly

Hello,

Im quite new to MicroStation and I've got the following thing:

When I only want to change the level a line or complex chain I use "change element attributes", and only check the box in front of "level". Then I choose the level to which I want to change the line or complex chain to.

When I follow those steps, the command changes the linestyle as well, while that box is unchecked. 

Can someone help me?