Fixed filters I want to eliminate

Anyone with access to "Customize this Report" can edit filter on a report. I don't know how to find who specifically changed it the last. An user name can be seen at the bottom usually at the record level, not on the report level.

To edit it back to where it was before, you need to click on the "Customize this Report"  on the top right corner and remove the filters that was added under the section "Filters".

It is also possible they modified the default report for the table - you'll know this if when you click "Customize this Report" you are shown the Table home page settings where you can specify the default report that each role sees when they click the table's icon in the top bar.

If that's the case, click the "Edit Settings" button to edit the default report for the table, then proceed with changing or removing the filters as Kingsly suggested.

Often times I think after users apply a filter to a report, especially the default, they click 'Save' not realizing this updates the default report settings.