I opened the Drawing Settings, and made some changes to the settings of the document I haveopen, but when I click OK, the Fixed Lengths have not changed for the existing structures.

I opened the Drawing Settings, and made some changes to the settings of the document I have open, but when I click OK, the Fixed Lengths have not changed for the existing structures.

Solution: This is as designed. All subsequent bonds drawn will be the new Fixed Length. If you want to change the existing structures so they will have the new Fixed Length, select the structures you want to change with the lasso tool, and then choose Scale from the Object Menu. Choose the first option (Scale selected objects so that median bond is Fixed Length).