Altium's way of handling libraries are not completely unified, if you change the schematic component, you have to update on the schematic document, if you change a footprint, you have to update on the PCB editor.

On the Schematic Editor

On your .SchDoc file, go to the drop down menu Tools→Update From Libraries

A window should appear, you can select which component to update from the schematic libraries, by default, all unique components in your .SchDoc are selected for updating. Click next if you wish to select individual parts for updating, otherwise, you can click Finish to update all schematic components.

On the PCB Editor

On your .PcbDoc file, go to the drop down menu Tools→Update From PCB Libraries

A window should appear, you can choose which layer on your board to compare, by default, all layers are selected. Click on "Update all Footprints (Create ECO)" to move on to the next step

You can select which individual components to update if desired, by default, all components are selected. To update, click on "Execute Changes".