By clicking on the point where you have the cut, you can press delete and the clips will turn into one clip again. It doesn’t matter if you click the out-point on the first clip or the in-point on the second clip.
Click the View in the top right corner of the Viewer and toggle Show Title/Action Safe Zones on or off.
In Final Cut Pro X, the boundaries are shown as yellow rectangles. Action Safe is the outer rectangle, Title Safe is the inner rectangle.
You can quickly apply fade-ins and fade-outs to selected clips or audio components from the Modify menu.
Choose Modify > Adjust Volume > Apply Fades.
You can remove one or more ranges from the browser or the timeline.
Clear one or more ranges in the browser or the timeline: Select the range or ranges, then choose Mark > Clear Selected Ranges (or press Option-X)
Remove all ranges in an event: Choose Edit > Select All (or press Command-A) to select all ranges in the current event, then choose Mark > Clear Selected Ranges (or press Option-X).
To change the connection point of an audio clip in Final Cut Pro X, you move the play-head to the spot you want.
Then press COMMAND+ALT and click on the audio track you want to connect the video clip you want to connect it to.
To keep the connected clip in place hold the Tilde ~ key and drag the clip to its new place.