diff --git a/ui/src/components/OperationPanel.jsx b/ui/src/components/OperationPanel.jsx
index ee43bd9..ba622da 100644
--- a/ui/src/components/OperationPanel.jsx
+++ b/ui/src/components/OperationPanel.jsx
@@ -786,17 +786,18 @@ export default function OperationPanel({
                        slices={slices} lookupDerivedCols={lookupDerivedCols} dimMembers={dimMembers} versionId={versionId}
                        extra={
                          <div className="flex flex-col gap-2">
-                           {/* Where the mix comes from. Left on the adjustable rows,
-                               clone behaves as it always did. Naming a segment reads
-                               from that entry instead -- including the reference ones
-                               operations are normally kept away from, which is the
-                               point: a period with no baseline borrows a shape from
-                               prior year or plan. */}
+                           {/* The selection is the SOURCE, not the destination: pick
+                               the cells you want to copy -- last December, say -- and
+                               the shift below is what lands them in the target period.
+                               Naming a segment narrows that selection to one entry,
+                               including the reference ones operations are normally kept
+                               away from, which is the point: a period with no baseline
+                               borrows its shape from prior year or plan. */}
                            <div className="flex items-center gap-2 flex-wrap">
-                             <span className="text-gray-500 whitespace-nowrap">copy from</span>
+                             <span className="text-gray-500 whitespace-nowrap">copy rows from</span>
                              <select value={cloneFrom} onChange={e => setCloneFrom(e.target.value)}
                                      className={`${INPUT} w-auto`}>
-                               <option value="">current selection</option>
+                               <option value="">the whole selection</option>
                                {(cloneSources || []).map(s => (
                                  <option key={s.id} value={s.id}>
                                    {s.label || `${s.operation} #${s.id}`}
@@ -818,11 +819,17 @@ export default function OperationPanel({
                                  <option value="24 months" />
                                  <option value="0 days" />
                                </datalist>
-                               <span className="text-gray-400 text-[11px]">
-                                 every date column, with period dimensions re-derived
-                               </span>
                              </div>
                            )}
+                           {cloneFrom && (
+                             <p className="text-gray-500 text-[11px] leading-snug max-w-sm">
+                               The cells you have selected are what gets copied. Shifting
+                               moves every date column, and the season and month
+                               dimensions are re-derived from the calendar to match — so
+                               select the period you are copying <em>from</em>, not the
+                               one you are filling.
+                             </p>
+                           )}
 
                            <div className="flex items-center gap-2">
                              <span className="text-gray-500">scale cloned rows by</span>