to exchange  - cambiar, intercambiar, canjear 

to trade  - comerciar, negociar, intercambiar, canjear 

to change  - cambiar, alterar, modificar, variar, transformarse, cambiar de, intercambiar 

to alter  - alterar, cambiar, modificar 

to transform  - transformar 

to confuse  - confundir, enturbiar, enredar, complicar 

to mix up  - confundir