RefTeX has a variable called
reftex-insert-label-flags. From the docstring:
reftex-insert-label-flags is a variable defined in
Its value is
Flags governing label insertion. First flag DERIVE, second flag
If DERIVE is t, RefTeX will try to derive a sensible label from
context. A section label for example will be derived from the section
heading. The conversion of the context to a valid label is governed by
the specifications given in
RefTeX fails to derive a label, it will prompt the user. If DERIVE is
nil, the label generated will consist of the prefix and a unique
If PROMPT is t, the user will be prompted for a label string. The
prompt will already contain the prefix, and (if DERIVE is t) a default
label derived from context. When PROMPT is nil, the default label
will be inserted without query.
So the combination of DERIVE and PROMPT controls label insertion.
Here is a table describing all four possibilities:
DERIVE PROMPT ACTION
nil nil Insert simple label, like eq:22 or sec:13. No query.
nil t Prompt for label.
t nil Derive a label from context and insert without query.
t t Derive a label from context and prompt for confirmation.
Each flag may be set to t, nil, or a string of label type letters
indicating the label types for which it should be true. The strings
work like character classes. Thus, the combination may be set
differently for each label type. The default settings "s" and "sft"
mean: Derive section labels from headings (with confirmation). Prompt
for figure and table labels. Use simple labels without confirmation
for everything else. The available label types are: s (section), f
(figure), t (table), i (item), e (equation), n (footnote), N
(endnote), plus any definitions in ‘reftex-label-alist’.
With the standard setting, you should achieve what you're asking for. Check the value and if it's somehow changed somewhere.