Maybe it's a personal preference, but disabling/changing the Date and Time stamp on an slide is quite hard if you don't know how to do it.
Editting is only possible when going go back to Insert --> Header and Footer. It isn't possible to right-click the date and time on the slide itself.
Steps to Reproduce:
1. Open Impress
2. Select default template
2. Insert --> Header and footer
3. Check: Date and Time
4. Click apply (all)
5. Try to edit Date and Time from the slide
Editting Date and Time is quite hard
Easy editting of Date and Time
User Profile Reset: YES
Build ID: 02ec51c7e0bf9320b32ec73233ecaaf160448776
CPU Threads: 4; OS Version: Windows 6.2; UI Render: default; Layout Engine: new;
TinderBox: Win-x86@62-merge-TDF, Branch:MASTER, Time: 2016-11-20_23:12:18
Locale: nl-NL (nl_NL); Calc: CL
User-Agent: Mozilla/5.0 (Windows NT 6.2; WOW64; rv:45.0) Gecko/20100101 Firefox/45.0
Updating the date is relatively easy : adding or duplicating a slide will update the timestamp for the whole presentation (assuming that this option was applied initially to all slides).
However, deactivating or removing the timestamp entry effectively requires the user to go back through the Insert > Header / Footer menu entry, which is less than intuitive.
Build ID: e1af58c1260f442c2731ae8a705deba732246b1d
CPU Threads: 2; OS Version: Mac OS X 10.12.1; UI Render: default; Layout Engine: new;
Locale: fr-FR (fr_FR.UTF-8); Calc: group
One for the UX people, methinks.
Yes it would be useful to be able to various footer fields within the document area and not have to open the dialog to do so.
Impress is not meant to flexibly modify the header/footer. These areas are reserved for the master level, though interactive elements that open the respective dialog on double-click might be handy sometimes.
As Alex states in c2 the workflow to change the date/time is straightforward, so I resolve this issue as WFM. Feel free to reopen.