Move Active Cursor left or right

I'm looking for some help when editing multiple lines. I can put the cursor on multiple lines by using Ctrl+Alt and up or down, but is there a way to move one cursor independently? I saw somewhere that I could do this with Ctrl+Alt+Shift and a direction, but that just moves the tab that I'm in. I'd really appreciate it as this was the code and I wanted to add in front of every occurrence of cell_counts as you can see below. Thanks again!

writeData(cell_counts, "control l1", control.l1)
writeData(cell_counts, "proportions control l1", prop.control.l1)
writeData(cell_counts, "control l2", control.l2)
writeData(cell_counts, "proportions control l2", prop.control.l2)
writeData(cell_counts, "control l3", control.l3)
writeData(cell_counts, "proportions control l3", prop.control.l3)

writeData(cell_counts, "sample l1", sample.count.l1)
writeData(cell_counts, "proportions sample l1", sample.prop.count.l1)
writeData(cell_counts, "sample l2", sample.count.l2)
writeData(cell_counts, "proportions sample l2", sample.prop.count.l2)
writeData(cell_counts, "sample l3", sample.count.l3)
writeData(cell_counts, "proportions sample l3", sample.prop.count.l3)