I followed the help suggestions for changing the spreadsheet tab name from “SheetN” to, say, “Summary”, but (a) the context menu shown when right-clicking on the sheet tab has no “Rename” selection, contrary to the help instructions, and (b) navigating from “Format” to “Sheet” to “Rename…” doesn’t work because “Rename…” is greyed out. The document was saved with a password, but I removed it and renaming is still blocked.
Renaming tabs in spreadsheet works fine for me in LibO 3.6.1.2. What format of file do you use? May be problem is whith this particular document.