Query!!! need advice on resequencing activities in P6

[Patchey]

I came across a problem trying to resequence the activities in P6. What happened is, I had to go back and rearrange the order in which activities were laid out. Originally I used at least a 5 or 10 number spacing to give me room for more tasks but found I could not resequence like I could do with P3. I had to paste and copy the entire project or go into the sub-sections and individually change the activities ID #

Is there a easy way to do this? or am I missing something?
Patchey