You can't change clip audio for clips that have already been brought onto the timeline. You can change a clip's audio interpretation by right-clicking, Modify, Audio Channels, which will change how it behaves each future time you bring in the clip, but won't retroactively change previous clips in a sequence.
That said, isn't super hard to replace. After doing the above, 'Mark Clip' your existing sequence clip to set an In/Out point in the sequence matching that clip's length, then press F to Match Frame. This will mark an In/Out in your source matching what you did previously. Then make sure your tracks are patched properly so only the new audio goes where you want and overwrite edit it in. Now your newly interpreted audio will be edited into where the clip was already.