You can move label callouts manually using the Move Label tool.
Hover over either end of a callout to see a red square anchor, click and drag, then click again to release.
To reset the callout to its default location, click and drag the callout anchor again but this time press Delete while it is active (highlighted green).
However... first you need to fix a bigger issue: all the data-defined overrides for your label callouts are invalid (red). It's likely your Label Anchoring Settings (Ancrage de l'étiquette > Paramètres in your screenshot) have invalid overrides as well.
Why this happens
The invalid icon usually shows up when you apply a style with overrides referring to a field that doesn't exist in your current layer.
This happens a lot with labels because using the label toolbar to move/customise individual labels and callouts auto-generates auxilliary fields that are auto-applied the data-defined override, but the user doesn't usually notice either the fields or the overrides.
So when a style is copied/saved from such a layer, then applied to a new layer that has not yet had these aux fields generated, the data-defined override fails. Crucially, once the style is applied, even if you do set up the aux fields later, the override continues to not work for some reason.
Solutions
There's two ways to fix it:
(a) Click on every single invalid data-defined override and select Clear, or
(b) Let the layer have a simple label style with no overrides (maybe paste one from a new scratch layer), move just one label and callout so the relevant aux fields are all generated, then apply the intended label style
If that layer's style was from a .qml you may wish to replace it - maybe do (a) on your layer and save that as the .qml, so it has none of the aux field overrides in the style definition. Either that, or be sure to only apply the .qml after you have generated the aux fields.