The TeXmaker documentation states
...(if some text has been selected in the editor before, the first "•" field will be replaced automatically by the selected text).
That is, subsequent "•" will not be filled in. So the functionality you desire does not seem to be built in to Texmaker.
Here's an alternative solution using TeXstudio, a fork of TeXmaker.
(Solution here is an adaptation from: https://tex.stackexchange.com/a/294698/117534)
What you are trying to achieve is replacing multiple placeholders with the same argument, which can be achieved in TeXstudio using the nifty "Mirrored Placeholders".
From within TeXstudio, you can set up user macros similar to user tags in TeXmaker:
Macros -> Edit Macros -> Add
Make the macro a
Normal type, and paste the following into the
LaTeX content box:
Finally, give the macro a name, in the
Name entry, for e.g. subsection.
The final result should look like this:
If your settings are default, you will be able to access this macro via Shift + F1 (or the other Fn keys if this is not your first macro).
If you are not sure, go to the
Macros menu and you should see your macro there.
A quick test: