With the Hammers still having conceded the most away league goals but the fewest at home in the Premiership, Glenn is looking for an improvement on the road - while maintaining the excellent home form.
He says: "It puts so much pressure on your home games when you are not even picking up the odd point away, and we really need to develop more of a killer instinct, especially away from home.
"I am not going to make excuses because I am not an excuse maker - we have just got to sort this away form out ourselves in the last five games.
"What exactly is behind the problem is really difficult to say, but we have conceded some stinking goals away from home this year and through hard work on the training ground, talking to the players, and more importantly the players doing it for themselves when they cross that white line, we need to do better away from home at both ends of the field.
"We have to improve defensively and, you'd have to say, in the attacking third as well because we are not looking like scoring as we are not making enough chances.
"There are a lot of things said before they go out - during the week, before kick off and at half time.
"There are a lot of reminders about what we should be doing and what we shouldn't be doing, but once they are across that white line and you leave them on their own they have got to make more right decisions than wrong ones."
The defeat at Bolton exacerbated the away goals against problem and, more to the point, means the Hammers have still only won on their travels three times this season, one of which was at Macclesfield in the FA Cup.
That said, in the 1997-98 campaign, when West Ham finished eighth and reached the quarter finals of both cups, the side lost 14 matches overall away from Upton Park, winning just four out of 23 games.
With 17 games away so far this season, one more away win would equal that number of wins on the road.
But, statistics apart, Glenn knows that the Hammers should have got at least a draw from the trip to the Reebok, and says: "It was difficult to find a lot of positives from losing at Bolton. I have got to say that, because we really went into the game with a belief that we would get at least something from the game.
"Even allowing for the fact that we had six regular and key first team players missing, I still felt that we should have had enough to have taken something from the game.
"Obviously a win was what we really wanted, but with the injuries and suspensions that we had we'd have taken a point; but it wasn't to be.
"There was nothing in it in the first half, other than the goal of course, which was sweetly struck.
"The marking was lax, the lad had time to size up what he was going to do, and again one player has let his concentration go because he should have been marking Gardner when the ball fell to him, instead of marking nobody inside the penalty box.
"Although it was a very well struck shot, it wasn't a great goal defensively from our point of view, and again we got so close to half time still in the game.
"The first real chance of the match fell to Jermain Defoe and the keeper made a good save, where this season Jermain has been scoring from that sort of situation.
"Nevertheless he hit the target, but the keeper made his block and that is what he is there for.
"They had one chance where Ricketts went clean through after a misunderstanding between two of the centre backs, but David James stood up, made himself as big as possible, and Ricketts knocked the ball against him.
"We spent the whole of the second half virtually camped in the attacking half and David James only had to field the ball.
"I can't remember anything worthwhile he had to do other than collect the ball and serve it but the disappointing thing was we didn't really open them up for enough clear chances.
"Having said that, there were three or four better than half chances that went begging."
Glenn was satisfied with Richard Garcia's performance and says: "Richard Garcia got his full debut when Don Hutchison pulled out on Friday evening with a sore groin.
"Richard was always going to be on the bench, but once Don pulled out it gave Richard an opportunity to start a Premiership game.
"It was a difficult game for him because there were so many first team players missing, but I have got no complaints with his full debut.
"He worked hard and showed in the game the form that he has shown in the reserves this season. He didn't leave anything behind in the dressing room and was as bitterly disappointed as everyone else was afterwards that we didn't get a result out of the game, especially as he felt he should have equalised with a header which just drifted a foot wide of the post.
"I have seen most of the reserve games this year and I have seen him score a couple of terrific headers this season - that was about the same sort of chance that he had been scoring from, but this time he knocked the header wide.
"Christian Dailly so nearly scored what I think would have been the winning goal against Chelsea when he hit the foot of the post and against Bolton, from a Labant corner, he has come in completely unmarked seven yards out and somehow managed to head the ball over the crossbar when you thought it would have been easier to at least get it on target.
"That missed chance summed up the whole day; it was very disappointing as we really needed to get at least a point up there."
Glenn was happy with Vladimir Labant's second start as well, and says: "I have to say Labant's service from corners and wide free kicks was excellent."
He hopes that the Slovakian turns out to be a bargain and adds: "He didn't cost as much as £1m, and it is much harder unearthing talent at that price than it is when you are spending a lot more money.
"That is stating the obvious - it is easier knowing a player's capability when he is in the millions of pounds class, because the ability is there for everyone to see.
"When you are spending less than £1m for a player at Premiership standard it is a lot easier to get it wrong.
"Sebastien Schemmel has turned out to be a good acquisition for less than £500,000 and worthy of calling himself a good Premiership player - and we are hoping Labant will do the same."