Check with whoever has the manager password to ensure it's enabled for your user.

Settings > User Management > Users

Edit the user

Under Level of Access, ensure Quotations is ticked

Click Finish

Thanks Jack. I hadn't thought of that, but I just checked; every single user has every option checked, including quotations, including the user who reported the issue.

It turns out though that my initial description was incorrect - the quotations option is showing for me in the nav bar, and also for the manager account - just not for this one affected user - although I've double-checked that quotations are enabled for her user account.

I'm going to get her to log in on a different machine and report back - might just be a local software issue.