Possible to change a topic's timestamp?

Those aren’t the right headers:

Once you have your API Key you can pass it in along with your API Username as an HTTP header like this:

curl -X GET "http://127.0.0.1:3000/admin/users/list/active.json" \
-H "Api-Key: 714552c6148e1617aeab526d0606184b94a80ec048fc09894ff1a72b740c5f19" \
-H "Api-Username: system"

and this is how POST requests will look:

curl -X POST "http://127.0.0.1:3000/categories" \
-H "Content-Type: multipart/form-data;" \
-H "Api-Key: 714552c6148e1617aeab526d0606184b94a80ec048fc09894ff1a72b740c5f19" \
-H "Api-Username: system" \
-F "name=89853c20-4409-e91a-a8ea-f6cdff96aaaa" \
-F "color=49d9e9" \
-F "text_color=f0fcfd"