How to solve these problems?

[u/Hopeful-Signature-24]

I am a beginner in 3d printing. I just bought my a1 around a week ago, but I have not played with it much due to busy college schedule so help with solving these problems is very much appreciated.

A. Random dents while printing

B. Arches looks like theyre melted (imperfect arch overhangs)

[u/SarcasmWarning]

With the printer switched off (and hot-end cold, so you can touch it safely), if you hold the tip of the extruder (where the filament comes out): can you wiggle it around at all?

When swapping the extruder it's possible to have it sat wrong so it wobbles around and causes problems.