How to restore earlier version of Numbers file on iPad Pro

I have been using icloud to backup my Numbers spreadsheet.

I want to find earlier version.

Following the instruction at Restore an earlier version of a spreadsheet in Numbers for iCloud – Apple Support (UK)

First step is

1. Open the spreadsheet, click the Tools button  in the toolbar, then choose Browse All Versions.

When I select tools I can't see "Browse all Versions"!

What am I doing wrong?

All help appreciated