I am changing color and thickness in tool option
but the balloon doesn't change. I want the balloon to have outline.
Tool option not working

The speech balloon doesn't seem to have an outline as part of its properties so you can't change something that doesn't exist. You need to create an outline shape for it.

Use the Contiguous Selection Tool (with Limit To Current Layer option box ticked) and click just inside the speech balloon. You will see a dotted selction outline around only the balloon. (If you click outside the balloon, you will also see a dotted line around the image border as well so be careful to click inside.)

Then do Select -> Convert to Shape and you will have a vector shape object that is the outline of the balloon.
Then do Select -> Deselect to remove the selection dotted outline.

Use the Select Shapes Tool to carefully select the outline shape. You can test that you have selected the outline (and not the balloon) by pressing the delete key to delete it, then Cntrl-Z to undo the deletion action.

Now, in the Tool Options docker, you can choose Solid Colour Fill and change the colour and line thickness of the outline.

You can also just try to ungroup the shape first. I think it's just groups that cannot have their fill stroke propagated.

I've just tried to Ungroup a speech balloon (right-click Ungroup) and that seems to have no effect that I can see. Further manipulation of the balloon didn't give me any outline effects.

ahabgreybeard wrote:I've just tried to Ungroup a speech balloon (right-click Ungroup) and that seems to have no effect that I can see. Further manipulation of the balloon didn't give me any outline effects.

You need to ungroup them twice. I guess we should consider a different outline for groups.

Yes, there are two levels of grouping, for some reason. If you do two Ungroup actions then the balloon is separated from its 'tail'. Each component, when selected, can then have its outline coloured and modified with the 'Solid Colour Fill' option.

However, this does not give the desired outline because you then have two separate overlapping outlines, where the tail joins the balloon.

If you use the whole object outline method I described above, you can carefully select the outline shape created, then shift-select the speech balloon to have both selected. Then you can right-click Group them to give a balloon with outline that can be moved and scaled as a single entity.

After this, a single Ungroup action will let you select the outline shape for colour/thickness/style change, followed by shift-click of the speech balloon to add it to the selection so you can Group them both, to be further treated as a single entity as required.

(Note that I am describing work on the 'Pepper & Carrot Speech Bubble' Library items. These are quite simple. The 'Word Balloons' Library items are more complicated and have drop shadows and highlighted edges which give a total of at least six elements all Grouped as one entity.)

Yes, you would need to use a logical operation(unite) on the speech balloons with tails to get the same effect.