I'm working on my thesis. ı tried to add same citation end of sentences. when ı add citation zotero numbering that citation for ex. "1". after that ı tried to add same citation to another sentence and it numbered 2. these are same citations and ı want to number them with same numbers. but ıt's not working
I'm assuming you're just using the wrong type of citation style -- footnotes are always sequential (i.e. they never repeat, including for the same item). If you want a style that repeats the number for the same reference, use a "numeric" style. Among those pre-packed that'd e.g. be Nature or Vancouver. There are many hundreds more on zotero.org/styles. Recall that you change citation styles for a document in your word processor under "Document Preferences".
https://www.zotero.org/support/reporting_problems#provide_steps_to_reproduce