Go to the published report on the server -> Click drop down arrow on the right -> choose manage -> choose parameters on the left pane. Under the 'Has Default' column, should be checked.
Under 'Default Value' it is either a specific explicit input or it will 'Query based' meaning it derives its value from a dataset or similar manner. If this is different you can just change it here.
If it is query based and your data cannot be altered here then go BIDS and open up the SSRS under the solution and select 'Open Folder in Windows Explorer'. Select your report's DATA file and delete it.
Note this is a file similar to it 'report.rdl.data'. Go to your report's project and choose 'Clean' then 'Rebuild' to remove all the data files in the bin in addition to one you did explicitly.
It builds all the files from the instructions. Preview your report, verify with defaults. Publish and observe.
If still did not changed report, then updates are not taking. Rename the report 'report_old' and try to publish again.
If problem continues then we check the publish location we want is valid and we are deploying correctly and that any parameters are not getting data from shared datasets that are not set to 'do not overwrite' or weird edge cases resulting from publishing being halted due to config settings.
Generally this is fixed with a rebuild.