Depends on the citation style -- which are you using? (Check under "Document Preferences") e.g. the "Vancouver" style that comes pre-installed uses (1), (2) etc.
The problem is the journal requires the use of the CSE Style (Council of Science Editors) for the bibliography, etc. It has the superscript as part of the correct style. However, the Journal does not allow superscript and wants the references number sequentially (1), (2), (3), etc. in the text. I tried for four hours to modify this and cannot figure out how or even if this can be done.
I'm not at my computer so cannot be specific right now. Many BMJ Group want "CSE-Vancouver" with ref numbers in parentheses and say that this format will be converted to superscripts upon publication. I seem to recall that many years ago, @adamsmith modified an existing Vancouver style (that used square brackets] at my request.
I'm asking because both Vancouver and CSE are frequently interpreted with some variations by journals, so before we go back and forth to get the style right, it's much easier to just look at the styleguide (and then presumably add it to the repository for everyone to use)
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CSE numbered style flavors are essentially Vancouver:
https://www.trentu.ca/academicskills/documentation-guide/cse-style/cse-vancouvercitation-name-end-references